Match LED Brightness

[codingwithethanol]

I'm helping a friend design a PCB badge for an event, I breadboarded a prototype and am now pricing out components from JLCPCB's SMT library. Something occurred to me though, which was a slight problem with the prototype. I used 2 different color LEDs, and identical resistors in parallel, but they were different brightness. How do I figure out how to keep them at identical brightness?

[mariush]

Well duh, human eyes have different sensitivity do different colors.

You could look into datasheets for those leds and see the numbers like mCd rating at some amount of current.

Also, different colors mean different forward voltages ... your formula is V = I x R  so  Resistor value = (Vin - Vdrop led) / I ... the resistors would be different.

You could always use a couple potentiometers instead of a resistor to limit current, and adjust the potentiometers under both leds look like the same brightness to you.

I'd suggest using a solar cell in a small box and measure the amount of current and voltage the solar cell gives when the led inside is lit... but solar cells are more sensitive to some parts of the light spectrum so it's probably not a good way to measure brightness.

[StillTrying]

"How do I figure out how to keep them at identical brightness"

By eye is the only way. I measured the max photo diode currents from some LEDs @ 5mA here, sometimes the brightness of SB green and blue were the other way around by eye, but SB green and blue were always at the top.
www.eevblog.com/forum/beginners/floating-probe!-for-$2-50/msg1858251/#msg1858251

[Kasper]

Edit to add: efficiency and viewing angle may be so different that these quick solutions do not help.
////////////////////////////////

Short version:
Pick resistors for each LED that cause them to have the same current.  For example if you want 5mA in each LED:
R = (Vsupply - Vf) / I
R = (Vsupply - Vf) / 0.005A

If they have similar current they should have somewhat similar brightness but you could go further...

Longer version:
Look up the amount of light output per current input and pick a current for each LED that will yield similar outputs.

Estimate Vf of each LED based on current.
This should be listed in datasheet maybe in a graph.

Use a different resistor for each LED:
R = (Vsupply - Vf) / I

[codingwithethanol]

EDIT: Just checked the thread and found that some other people replied

@mariush
Yeah its just that I'm picking SMD leds I haven't used irl so the last thing I need is for my friend to get like 100 of them and one color is far brighter than the other. Just to make sure, what you're saying is I need to design it so that mCd is matched?

@StillTrying
I'm trying to spec out blue and yellow LEDs, I have some THT ones but SMD is a mystery.

@Kasper
I took mariush's advice and looked through the datasheets and found mCd ratings and "relative luminous intensity", and just wanted to make sure that I have my maths correct.

[codingwithethanol]

Not sure how to interpret the mCd ranges

[wraper]

It's naive to expect different color LEDs to have the same brightness. Even if you take same model LEDs from different batches, brightness or color tone may be noticeably different. Also their forward voltage vary, so you will get not only different current with the same resistor but also different power even if current is the same. If you look into datasheets for similar LEDs, maximum available brightness for different colors is quite different. Not to say eyes have different sensitivity to different wavelengths.

[StillTrying]

@StillTrying
I'm trying to spec out blue and yellow LEDs, I have some THT ones but SMD is a mystery.

It wouldn't surprise me if the yellow needs 50%+ more current than the blue to look similar brightness.

[mariush]

Not sure how to interpret the mCd ranges

The led will produce a certain amount of light intensity at a particular current amount.
If you restrict the current by adjusting the resistor, you'll have less brightness.

In your pictures, it's not really 100% clear what they mean. I may be wrong, but I read it as the led being capable of around 45-55mCd and that's probably 1 on the Y axis on that chart.
Increasing the current to around 20mA would result in 1.2 x 45-55 mCd and lowering to 10mA would result in 0.8x45-55 mCd.
Of course, may be totally wrong.

I'd suggest buying better leds, from better distributors like Digikey, Mouser, Farnell/Newark etc
At least you get proper datasheets...

[wraper]

I'd suggest buying better leds, from better distributors like Digikey, Mouser, Farnell/Newark etc
At least you get proper datasheets...

It's not like buying there will provide you with brighter LEDs. You can easily buy expensive LED from reputable manufacturer made with old technology and piss poor brightness. As far as it seems those LEDs have good enough datasheets according to screenshots.

[mariush]

It's not like buying there will provide you with brighter LEDs. You can easily buy expensive LED from reputable manufacturer made with old technology and piss poor brightness. As far as it seems those LEDs have good enough datasheets according to screenshots.

Wasn't referring to brightness, but about how clear and easy to parse/read/understand datasheets are.
For example, see these which are 0.08$ at 100 : https://www.digikey.com/product-detail/en/lite-on-inc/LTST-C190KFKT/160-1434-1-ND/386812
Here's datasheet: http://optoelectronics.liteon.com/upload/download/DS-22-99-0186/LTST-C190KFKT.PDF

Has everything he needs to know... mCd rating , mCd rating depending on bin version (page 6) , charts on page 7 of the pdf

[codingwithethanol]

@StillTrying
Thats a big yikes! The whole thing is going to run off a CR2032 so i'm trying to keep current to a minimum. Alot of these LED's i'm seeing are trying to pull 20mA.

@mariush
Yeah i'm restricted to parts from JLCPCB's part library, so we can get the badges fully assembled. Trying to see if I can find some not so scuff LEDs in the list.

@wraper
Not so much brightness that i'm concerned with, just uniformity.

[wraper]

@StillTrying
Thats a big yikes! The whole thing is going to run off a CR2032 so i'm trying to keep current to a minimum. Alot of these LED's i'm seeing are trying to pull 20mA.

They are not trying to pull anything. Small LEDs usually have 20 mA maximum current rating. Actual current depends only on you. If you are concerned about battery life, select brightest (most efficient) LEDs thus needing lowest current for required brightness.

@wraper
Not so much brightness that i'm concerned with, just uniformity.

Then you don't need to change LEDs to begin with. Just select current limiting resistors to get required brightness.

[StillTrying]

@StillTrying
Thats a big yikes! The whole thing is going to run off a CR2032 so i'm trying to keep current to a minimum. Alot of these LED's i'm seeing are trying to pull 20mA.

I don't know about SMD, but close up I can see a Super bright 5mm blue lit at less than 1uA, they're very bright at 1 or 2mA.

[sleemanj]

The best way to match an led for brightness, with a resistance decade box and your eyeball.

Decide on a resistor for one led that produces the brightness you want, then hook your decade box up for the second led and adjust until you find something that makes them match.

[wraper]

The best way to match an led for brightness, with a resistance decade box and your eyeball.

Decide on a resistor for one led that produces the brightness you want, then hook your decade box up for the second led and adjust until you find something that makes them match.

Not everyone has resistance decade box. Using potentiometer instead of fixed resistor to adjust the brightness and then measuring it's resistance would do the job just as well.

[BravoV]

I don't know about SMD, but close up I can see a Super bright 5mm blue lit at less than 1uA, they're very bright at 1 or 2mA.

In my limited experiences, looking straight directly at the LED light path is very poor way to perceive it's brightness level at 1 or 2 mA (@20 mA rated LED) as they're still blinding, try shine it to a wall or bright object, or use two identical LEDs with different current to see the "optimal" brightness vs current.

[Whales]

Side question: Do you need the LEDs to appear similar at close range or very long range (eg crowds)?

Keep in mind that different LEDs have different output angles.  At close range things can match, but if you care about 50-100m away then make sure to tune them at that distance.  Different output cones == different rates of decay with distance, ignoring the problems of off angles.

[tooki]

Blue LEDs are all made with “modern” ultra high efficiency compositions. Red, yellow, and green (especially yellow) are often older, less efficient chemistries. (Modern emerald green LEDs can be insanely efficient. As power indicators, I usually run them at about 0.5mA.) The result is that at a given current, the blue LED can be massively brighter.

You can get a sort of broad idea as to the chemistry by the forward voltage: for a given color, a higher voltage tends to be more efficient. So for example a traditional green LED might be 2.2V, while a modern high efficiency one is 3.2V.

In any case, I totally agree with the recommendation to do some testing and basically adjust it by eye using potentiometers until you’ve found what values work. Between LED chemistry, human eye characteristics, and optical characteristics of different LEDs, there’s just no real way to rely on calculations alone.

[Psi]

Short version:
Pick resistors for each LED that cause them to have the same current.  For example if you want 5mA in each LED:
R = (Vsupply - Vf) / I
R = (Vsupply - Vf) / 0.005A

If they have similar current they should have somewhat similar brightness but you could go further...

Doesn't really work.
At the same current, or even the same wattage there can be a huge difference in brightness.
The efficiency of LEDs varies a lot by color and by the chemistry used.
Even for one color, like yellow, there are a few different chemistry that can be used and they can have wildly different efficiency.

Best thing to do is look at the mcd rating and only compare leds that have the same viewing angle.
That will match them up pretty well.

[exe]

I had the same problem and I used my eyes and individual resistors for three different leds (red, green, and orange).

BTW leds vary wildly when it comes to efficiency. I bought more than 10 different kinds to understand what I need. At the end I used leds with highest efficiency because why wasting power.

[tooki]

Short version:
Pick resistors for each LED that cause them to have the same current.  For example if you want 5mA in each LED:
R = (Vsupply - Vf) / I
R = (Vsupply - Vf) / 0.005A

If they have similar current they should have somewhat similar brightness but you could go further...

Doesn't really work.
At the same current, or even the same wattage there can be a huge difference in brightness.
The efficiency of LEDs varies a lot by color and by the chemistry used.
Even for one color, like yellow, there are a few different chemistry that can be used and they can have wildly different efficiency.

Best thing to do is look at the mcd rating and only compare leds that have the same viewing angle.
That will match them up pretty well.

Exactly. When I was writing my prior reply, I dug out some old green LEDs from around 1990 and a modern green LED. At 20mA, the old green LED is far dimmer than the modern LED at 0.5mA. The modern LED at 20mA is blindingly bright.

[Kasper]

Short version:
Pick resistors for each LED that cause them to have the same current.  For example if you want 5mA in each LED:
R = (Vsupply - Vf) / I
R = (Vsupply - Vf) / 0.005A

If they have similar current they should have somewhat similar brightness but you could go further...

Longer version:
Look up the amount of light output per current input and pick a current for each LED that will yield similar outputs.

Estimate Vf of each LED based on current.
This should be listed in datasheet maybe in a graph.

Use a different resistor for each LED:
R = (Vsupply - Vf) / I

Short version:
Pick resistors for each LED that cause them to have the same current.  For example if you want 5mA in each LED:
R = (Vsupply - Vf) / I
R = (Vsupply - Vf) / 0.005A

If they have similar current they should have somewhat similar brightness but you could go further...

Doesn't really work.
At the same current, or even the same wattage there can be a huge difference in brightness.
The efficiency of LEDs varies a lot by color and by the chemistry used.
Even for one color, like yellow, there are a few different chemistry that can be used and they can have wildly different efficiency.

Best thing to do is look at the mcd rating and only compare leds that have the same viewing angle.
That will match them up pretty well.

Exactly. When I was writing my prior reply, I dug out some old green LEDs from around 1990 and a modern green LED. At 20mA, the old green LED is far dimmer than the modern LED at 0.5mA. The modern LED at 20mA is blindingly bright.

Quoting people doesn't really work if you don't read their whole post or the original post.

My post was clearly broken into a quick solution for someone who seems to want a quick solution and then a better solution with an explanation that the quick solution is not great.

You quote the 1st half of my post, say it doesn't really work (as if I didn't just say that) and then you go on to repeat the 2nd half of my quote which you for some reason left out.

Your whole post could have been better written in 1 sentence: 'viewing angle should also be matched'.

OP also said parts are coming from JLCPCB's SMT library so I doubt 1 is 30 years old and the other is modern.

[Siwastaja]

My post was clearly broken into a quick solution for someone who seems to want a quick solution and then a better solution with an explanation that the quick solution is not great.

Doesn't matter. Sorry to say, but your "quick" "solution" is just plainly wrong, and won't work as a "first order estimate" to be improved upon. It's waste of time, and misleading.

LED efficiencies easily vary by two orders of magnitude. Assuming current has anything to do with brightness is just wrong. It's not even about the age of the LED - very inefficient and dim LEDs are still being made, especially green.

The quick solution is to look at mCd numbers in datasheets, if available. The better solution is finetuning by eye.

Choosing the most efficient (bright) LEDs is a good start, also to save energy. Then fine-tune by adjusting resistors - this is done by eye.

So following your solution, you should go in the opposite direction, from step 2 to step 1.

[Kasper]

My post was clearly broken into a quick solution for someone who seems to want a quick solution and then a better solution with an explanation that the quick solution is not great.

Doesn't matter. Sorry to say, but your "quick" "solution" is just plainly wrong, and won't work as a "first order estimate" to be improved upon. It's waste of time, and misleading.

LED efficiencies easily vary by two orders of magnitude. Assuming current has anything to do with brightness is just wrong. It's not even about the age of the LED - very inefficient and dim LEDs are still being made, especially green.

The quick solution is to look at mCd numbers in datasheets, if available. The better solution is finetuning by eye.

Choosing the most efficient (bright) LEDs is a good start, also to save energy. Then fine-tune by adjusting resistors - this is done by eye.

So following your solution, you should go in the opposite direction, from step 2 to step 1.

Quick solution would most likely be better than using the same resistor for each LED.

[Kasper]

To add, op said they are sourcing from JLCPCB smt library so I am guessing the 2 leds are not on opposite sides of the efficiency spectrum.  If op chooses the most expensive of one color and the cheapest of the other color that probably won't help.

[Kasper]

I edited my earlier post to add: efficiency and viewing angle may be so different that these quick solutions do not help.

[tooki]

As Siwastaja said, they still make the old-style low efficiency LEDs, which was my point (I dug out an actual old one simply because it was a sure way to ensure it wasn’t an efficient chemistry).

But no, your first method isn’t any help in practice. As Siwastaja also said, LED efficiency spans multiple orders of magnitude, even among modern LEDs. Choosing a similar drive current tells you nothing about whether two different LEDs will have similar light output.

[Zero999]

@StillTrying
I'm trying to spec out blue and yellow LEDs, I have some THT ones but SMD is a mystery.

It wouldn't surprise me if the yellow needs 50%+ more current than the blue to look similar brightness.

Yes, that's certainly true of old yellow LEDs. A much better alternative is to use phosphor converted LEDs which are just deep blue/violet/UV LEDs with a yellow phosphor. They have a higher forward drop, but are much more efficient than the crappy old LEDs and have a much broader spectrum, so are often specified in chromaticity, rather than dominant wavelength.
https://static.rapidonline.com/pdf/55-9182.pdf

[Kasper]

As Siwastaja said, they still make the old-style low efficiency LEDs, which was my point (I dug out an actual old one simply because it was a sure way to ensure it wasn’t an efficient chemistry).

But no, your first method isn’t any help in practice. As Siwastaja also said, LED efficiency spans multiple orders of magnitude, even among modern LEDs. Choosing a similar drive current tells you nothing about whether two different LEDs will have similar light output.

Best thing to do is look at the mcd rating and only compare leds that have the same viewing angle.
That will match them up pretty well.

I looked up 7 different smt LEDs on JLCPCB parts list.  Just used ones rated at 20mA.

Did not even find 1 order of magnitude difference in efficiency.  And found they all had similar viewing angles.

MPN:
   Yellow:
      19-213/Y2C- CQ2R2L/3T(CY), 17-21SUYC/TR8, FC-DA1608HYK-588J, E6C0805UYAC1UDA
   Blue:
      X L - 0 8 0 5 Q B C, E6C1206QBAC1UDA, MHT170UBCT
      
Yellow:
   Intensity: Min, Typ, Max (MCD): 70, 125, 220
   View angle: Min, Max: 120°, 130°
   Typ Vf: 2V
      
Blue:
   Intensity: Min, Typ, Max (MCD): 50, 111, 225
   View angle: Min, Max: 120°, 140°
   Typ Vf: 3V
   
Comparing yellows to blues, there was much less difference in intensities and viewing angles than there was in Vf.

Resistor voltage with 3.3V supply:
      Vr_yellow = 3.3V - 2V = 1.3V
      Vr_blue = 3.3V - 3V = 0.3V

Example currents with 3.3V supply and 65 ohm resistor:
   If_yellow = 20mA
   If_blue = 5mA
   
Typical luminous intensity at 20mA:
   Yellow: 125 MCD
   
Typical luminous intensity at 5mA (based on linear approximation of current vs luminous intensity):
   Blue: 28 MCD
   
Results:
   Difference in typical MCD based on using same value resistor for both LEDs: 125 MCD / 28 MCD
   4.5 times difference

   Typical difference in MCD between yellow and blue: 125 MCD / 111 MCD
   1.1 times difference

   Worst case difference in MCD (max yellow / min blue): 220 MCD vs 50 MCD
   4.4 times different

Conclusion:
   In this case difference in Vf is as impactful as difference in efficiency. 
   If you go on digi-key and look up the extremes then you can find some big differences in efficiency but that comes with different packages and different costs.  Odds are the purchaser is going to choose identical packages and similar costs and it seems like that will yield similar efficiencies. At least similar enough that there is room for current matching to cause an improvement in intensity matching.
   

[tooki]

Well, I just grabbed the electronics catalog that happened to be closest at hand (in this case, Reichelt) and on the first page of LEDs alone, just within the 3mm (T1) LEDs, the light output of the LEDs listed spans 3 mcd to 14,000 mcd at the same current in the same package. Yes, differences in viewing angle account for some of that, but my point remains that "Choosing a similar drive current tells you nothing about whether two different LEDs will have similar light output."

If you're starting by selecting two LEDs with similar rated output at the same current, as you did, then yeah, current tells you something. But if you're looking at LEDs as a whole, it tells you nothing.

[Psi]

I remember when i designed some ID badges for a gaming event around 7 years ago.
I did some datasheet research looking at 100's of leds to find the most efficient LED i could.
We wanted the ID badge lighting to last for 3 days straight on two CR2032 but be as bright as possible.

I bought around 30 LEDs from digikey that looked promising and ended one with a InGaN/GaN orange LED that was amazing. 
At 1mA it was about the same brightness as most others are at 20mA.

[Kasper]

If you're starting by selecting two LEDs with similar rated output at the same current, as you did, then yeah, current tells you something.

Before accusing me of cherry picking my data, you should look at their site.  Relying on such a big assumption just shows you don't have a good argument.

I did not select LEDs with similar rated outputs on purpose.  I got LEDs with similar rated outputs because that's what is on their site. 

I didn't even limit my selection for package size, viewing angle or cost.  I selected the first handful of blues and yellows.

There were a couple with lower intensity but they also had lower current so I did not include them and I was clear about that filtering for 20mA.  I almost included them as extra evidence of my argument that lower current generally yields lower output but my post was already too long.

[tooki]

If you're starting by selecting two LEDs with similar rated output at the same current, as you did, then yeah, current tells you something.

Before accusing me of cherry picking my data, you should look at their site.  Relying on such a big assumption just shows you don't have a good argument.

Bro, you lost the disagreement long ago. You made a claim that is readily disproven, and multiple people have done just that. You’re just making yourself look silly by digging in your heels on something that is so easily disproven.

Anyhow, I didn’t say you cherry picked your data. You selected LEDs with broadly similar light output. How that came to be is irrelevant. You chose randomly and so did I when I literally grabbed the closest catalog at hand. But the upshot is, your claim that LEDs of similar current will have similar brightness is plain and simply not true.

[Zero999]

I remember when i designed some ID badges for a gaming event around 7 years ago.
I did some datasheet research looking at 100's of leds to find the most efficient LED i could.
We wanted the ID badge lighting to last for 3 days straight on two CR2032 but be as bright as possible.

I bought around 30 LEDs from digikey that looked promising and ended one with a InGaN/GaN orange LED that was amazing. 
At 1mA it was about the same brightness as most others are at 20mA.

It sounds like a phosphor converted LED, similar to the one in the datasheet, I linked previously. Do you have the part number or data sheet?

I found the same yolk yellow LED in TME, for those in Europe who'll find it easier to order it from there, than Rapid. No doubt a similar type of LED can be found in the US.
https://www.tme.eu/gb/details/oscm4l5111a/tht-leds-5mm/optosupply/

[Kasper]

If you're starting by selecting two LEDs with similar rated output at the same current, as you did, then yeah, current tells you something.

Before accusing me of cherry picking my data, you should look at their site.  Relying on such a big assumption just shows you don't have a good argument.

Bro, you lost the disagreement long ago. You made a claim that is readily disproven, and multiple people have done just that. You’re just making yourself look silly by digging in your heels on something that is so easily disproven.

Anyhow, I didn’t say you cherry picked your data. You selected LEDs with broadly similar light output. How that came to be is irrelevant. You chose randomly and so did I when I literally grabbed the closest catalog at hand. But the upshot is, your claim that LEDs of similar current will have similar brightness is plain and simply not true.

Once again you prove you have no good argument by choosing fallacies over details.

[Nusa]

Keep in mind that fine-tuning by eye assumes that everyone that's going to use the device has the same eyes. Color perception varies greatly among the population.

[codingwithethanol]

WOW!

Lot of replies, not sure how to respond but i'm at least glad I started an interesting line of discussion. For the time being i'm going to design the circuit with same color LEDs, but in the future i'd actually like to order a variety of SMD LEDs and settle this via experimental data once and for all. I'll bump this thread when the badges come in so keep an eye out.

[Psi]

It sounds like a phosphor converted LED, similar to the one in the datasheet, I linked previously. Do you have the part number or data sheet?

My notes from back then are a bit of a mess.
But i think it was this one
https://www.digikey.com/product-detail/en/kingbright/WP7104SYC/754-1257-ND/1747656
I don't think it was a 'special' led.

I ordered around 30 different leds based on their datasheet specs and price.
Out of the 30 that one was the brightest for the least current.

[Kasper]

WOW!

Lot of replies, not sure how to respond but i'm at least glad I started an interesting line of discussion. For the time being i'm going to design the circuit with same color LEDs, but in the future i'd actually like to order a variety of SMD LEDs and settle this via experimental data once and for all. I'll bump this thread when the badges come in so keep an eye out.

I applaud your enthusiasm but I think a digikey search would be a more thorough way to settle it though even that is left open to arguments over how tightly it should be filtered for package size, viewing angle, current, cost, etc.

On a side note, I am interested what the part numbers were for the 2 LEDs that you were talking about at the start of this.  That is too small of a sample to really prove anything, but I am curious.

[tooki]

If you're starting by selecting two LEDs with similar rated output at the same current, as you did, then yeah, current tells you something.

Before accusing me of cherry picking my data, you should look at their site.  Relying on such a big assumption just shows you don't have a good argument.

Bro, you lost the disagreement long ago. You made a claim that is readily disproven, and multiple people have done just that. You’re just making yourself look silly by digging in your heels on something that is so easily disproven.

Anyhow, I didn’t say you cherry picked your data. You selected LEDs with broadly similar light output. How that came to be is irrelevant. You chose randomly and so did I when I literally grabbed the closest catalog at hand. But the upshot is, your claim that LEDs of similar current will have similar brightness is plain and simply not true.

Once again you prove you have no good argument by choosing fallacies over details.

Your claim has been completely disproven, end of story. No fallacies, no cherry picking. Your stubbornness is astounding, given that it’s literally trivial to disprove your claim. One 20mA LED with 3mcd, another 20mA LED with 14,000mcd. Not even in the same ballpark of brightness.

[james_s]

Buy some samples of the LEDs you wish to use, then experiment with variable resistors to get the brightness you want. Measure the resistance of the pots then and select fixed resistors of similar value.

This is waaay easier than trying to calculate from the datasheets and will give better results anyway. You're always going to need a different resistor value for each color, the forward voltage for example of a red LED is usually around half that of a blue LED.

[kripton2035]

a device like this one may help too.
http://www.neufeld.newton.ks.us/electronics/?p=1145

[Kasper]

If you're starting by selecting two LEDs with similar rated output at the same current, as you did, then yeah, current tells you something.

Before accusing me of cherry picking my data, you should look at their site.  Relying on such a big assumption just shows you don't have a good argument.

Bro, you lost the disagreement long ago. You made a claim that is readily disproven, and multiple people have done just that. You’re just making yourself look silly by digging in your heels on something that is so easily disproven.

Anyhow, I didn’t say you cherry picked your data. You selected LEDs with broadly similar light output. How that came to be is irrelevant. You chose randomly and so did I when I literally grabbed the closest catalog at hand. But the upshot is, your claim that LEDs of similar current will have similar brightness is plain and simply not true.

Once again you prove you have no good argument by choosing fallacies over details.

Your claim has been completely disproven, end of story. No fallacies, no cherry picking. Your stubbornness is astounding, given that it’s literally trivial to disprove your claim. One 20mA LED with 3mcd, another 20mA LED with 14,000mcd. Not even in the same ballpark of brightness.

I counted 6 fallacies in your last post, 7 if you count the values without links or even part numbers.  I use evidence and you use fallacies.  It does not look like I am wrong.  If I am, please give explanation instead of spewing fallacies.

I gave you a chance and dug through JLC library to learn more and I learned you were wrong.  I shared my findings, you replied with nothing but fallacies.  You finally tried to share some evidence though without part numbers it really is just another fallacy.  I gave you another chance and looked on digikey and once again I find that you are exaggerating. 

Digikey.ca search: LED - discrete, smt, in stock, 20mA, blue and yellow.  Min intensity: 3.2 mcd.  Max intensity: 5700 mcd

That is huge range, still smaller than your numbers because you exaggerate too much.  Odds of someone ordering 1 on either side of that range are slim.  Odds are they will pick identical packages and similar costs.

If the search is narrowed by package:
0603: 6 mcd  - 1600 mcd
0805: 4 mcd - 1990 mcd

Still a large range but odds of purchaser choosing one on either end of that spectrum are slim.  If they choose cheapest LEDs or most in stock, the range is significantly reduced.

Cheapest 10 in package 0603, cut tape:
   intensity: 63 mcd - 170 mcd
   viewing angles: 120° - 140° (2/10 not listed)

Highest stock 10 in package 0603, cut tape:
   intensity: 104 mcd - 800 mcd (8/10 are between 104 mcd and 180 mcd)
   viewing angles: 60° - 130° (8/10 are between 120° and 130°)
   
This helps explain why I found such a limited range of intensities and viewing angles when I looked on the library in question, JLC's library.

If you must continue, please give evidence instead of fallacies.

[Zero999]

Of course simply selecting the same forward current doesn't give equal brightness for two different colour LEDs, even if differences in beam angle are taken into account. Implying that it's a good rule of thumb, is just not true. As mentioned above, the radiometric efficiency depends on the chemistry and the luminous efficacy, depends on the sensitivity of the human eye to the light being produced. A classic example is a royal blue vs modern, high efficiency emerald green LED. The royal blue LED will have a better radiometric efficiency i.e. optical power out, in the visible spectrum vs electrical power in, but the emerald green LED will look brighter and have a higher luminous efficacy because the human eye is much more sensitive to that colour. It will also depend on whether the observer's eyes are dark adapted or not. In low light conditions, the peak sensitivity of the human eye shifts to shorter wavelengths, which will suppress reds and accentuate blues. In bright daylight, the reverse happens.

Going back to the original post, it might not even be desirable to have all colours equal brightness, because it will probably look unnatural. The blue and red LEDs will look much brighter than they should be and the green and yellow LEDs much dimmer. It might make more sense to make each LED emit the same optical power, or scale the optical power output, to the expected black body spectrum of an object at a certain temperature.
https://en.wikipedia.org/wiki/Black-body_radiation#Spectrum
https://upload.wikimedia.org/wikipedia/commons/1/19/Black_body.svg

[tooki]

If you must continue, please give evidence instead of fallacies.

Wow man, what a joke.

I don’t even think you know what a fallacy means. Your reply only serves to confirm what I have been saying. 

I didn’t limit myself to what jlcpcb carries, nor to only blue and orange, because your original claim didn’t, either. You made a broad general statement that simply isn’t true, and not only have I and others disproven it, now you have done the same. 

I don’t need to provide part numbers and links for my statement to be true. I gave you the source (the Reichelt catalog), and if you wanted to, you could go find it. (It is online.) I certainly am not going to go out of my way for someone who is so utterly arrogant in their position that it’s clear that NOTHING will make you realize you’re spouting bullshit.

[Kasper]

Edit to add: efficiency and viewing angle may be so different that these quick solutions do not help.
[...]
If they have similar current they should have somewhat similar brightness but you could go further...

Longer version:
Look up the amount of light output per current input and pick a current for each LED that will yield similar outputs.
[...]

Of course simply selecting the same forward current doesn't give equal brightness for two different colour LEDs, even if differences in beam angle are taken into account. Implying that it's a good rule of thumb, is just not true.
[...]

I gave a quick solution that probably would have been an improvement.  Not hard to improve on using the same resistors for different colors.  Using the words 'should' and 'somewhat' I explained it is not a great solution and went on to describe a better solution.  I even went back to clarify there may be cases where it doesn't help.  Even though it most likely would have helped with LEDs from where OP is sourcing (JLC) or even with LEDs from digikey as I have clearly shown.

[Kasper]

If you must continue, please give evidence instead of fallacies.

Wow man, what a joke.

I don’t even think you know what a fallacy means. Your reply only serves to confirm what I have been saying. 

I didn’t limit myself to what jlcpcb carries, nor to only blue and orange, because your original claim didn’t, either. You made a broad general statement that simply isn’t true, and not only have I and others disproven it, now you have done the same. 

I don’t need to provide part numbers and links for my statement to be true. I gave you the source (the Reichelt catalog), and if you wanted to, you could go find it. (It is online.) I certainly am not going to go out of my way for someone who is so utterly arrogant in their position that it’s clear that NOTHING will make you realize you’re spouting bullshit.

I politely request evidience instead of fallacies, I even said please but once again you reply with more fallacies and personal attacks 'utterly arrogant' and 'spouting bullshit' and a even little yelling 'NOTHING'.

I certainly am not going to go out of my way for someone who is so utterly arrogant in their position that it’s clear that NOTHING will make you realize you’re spouting bullshit.

You won't go out of your way to share knowledge but you are going out of your way to spew fallacies and personal attacks.  I guess we know what you are here for.

Fallacies and attacks are clearly your top priority but if you are going to call someone wrong, you should expect them to ask why.

blue and orange

blue and yellow.

[tooki]

We’ve told you why you’re wrong. You already provided evidence of this yourself. But since you won’t accept your own evidence as evidence, it’s clearly utterly pointless to go to the much greater effort to dig up datasheets and stuff.

P.S. They’re not personal attacks, just simple statements of fact.