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NiHaoMike:
--- Quote from: bsfeechannel on July 01, 2019, 04:16:28 pm ---I try to keep the resolution of my drawings, photos and screen captures less than VGA (640x480). When they're "big", HD (1280X720), tops.
--- End quote ---
That seems way outdated in today's day and age. I generally target 1080p except when it would clearly be overkill or is insufficient to show relevant detail. Pretty much every PC monitor I see for sale nowadays is at least 1080p. Once 1440p or 4K becomes mainstream to the extent 1080p is now, that would become my new target.
RoGeorge:
For the PNGs is pretty straightforward how to minimize their side. Unfortunately PNG is good only for schematics or screen captures, where there are large areas of the same color. PNG is not compressing well when there are variable shades and colors, as pictures usually have.
For pictures JPG is still the best compromise. I tried a few resolutions at different compressions for JPGs.
If the pics are resized to 1024x768 then exported with 50% compression (from Gimp), then the size is reduced from a typical 2MB (for my Z1 camera) to only 30...70KB.
As an example, a huge post like this, https://www.eevblog.com/forum/projects/measure-a-magnets-b-field-with-a-rigol-ds1054z-oscilloscope-and-a-piece-of-wire/ with 4 photos and 6 oscilloscope screen's captures, all embedded at full size between text, has only 500KB in total! 8)
Thank you all for the help :)
bsfeechannel:
--- Quote from: Zero999 on July 01, 2019, 06:17:04 pm ---Just use Gimp to reduce the image to indexed, with a maximum palette of 256 colours and export to PNG. PNG supports 1-bit, 4-bit and 8-bit indexed modes and Gimp will automatically select the correct one, so it it has two colours, you'll get a 1-bit PNG.
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Ha! Awesome! I managed to reduce an 8-bit png image from 37kB to just 1-bit 2.8kB. My free-hand trace appears a little jagged (because of the loss of the smoothing gray scale) , but what the heck? The resulting file is less than one tenth of the original file in size. Thanks a bunch for the tip.
--- Quote from: NiHaoMike on July 01, 2019, 07:48:14 pm ---That seems way outdated in today's day and age. I generally target 1080p except when it would clearly be overkill or is insufficient to show relevant detail. Pretty much every PC monitor I see for sale nowadays is at least 1080p. Once 1440p or 4K becomes mainstream to the extent 1080p is now, that would become my new target.
--- End quote ---
Well I always think of the cell phone viewers with low resolution screens and/or slow/limited bandwidth connections.
I think these resolutions provide a reasonable experience on both mobile and desktop. If I ever have to show for some reason a larger picture, I'll leave it as the default clickable thumbnail at the end of the message.
NiHaoMike:
The mobile site is different from the desktop version, and that's where the suggestion to upsize the thumbnails really helps - make them double as the default mobile images!
Berni:
Yeah monochrome PNG for diagrams is a big time space saver, GIF also does pretty well here.
But you certainly don't want to save a photo as a PNG. Because of it being a losses format it tries to perfectly replicate the noise and compression artifacts and this results in files that are many times larger than JPEG. But those big 5MB JPEGs from a modern phone camera can certainly be squeezed down a lot. The image quality of such photos is often not that great anyway so there is no major quality loss in resampling the image to 1/2 scale or turning up the jpeg compression factor higher.
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