I think there is a reason for the marketing guy to request 300dpi images even for web material, as those images would look nicer on a device with high DPI display (like recent iPhones, or people with 4K monitors - I have both, and it does make a difference.)
Nah, it's a holdover from the print era, plain and simple.
The pixels on those HiDPI monitors are so small that pixel-for-pixel display of traditional user interface would be too small to read or use. So for those HiDPI monitors either they have to prepare a vector image or higher DPI image to display pixel for pixel, or allow the image scaling algorithm to ruin the entire user interface. HiDPI sort of forced some print era solutions to resurface, as the screens now have similar dpi resolution as the printers.
We aren't talking about user interfaces. We're talking about marketing photos.
Hi Guys,
Looks like there is a lot of confusion here in regard to dpi and printing.
Lets take an image of 330 pixels wide and 300 pixels high ¿ OK ? and look at this image on the monitor. 300x300 pixels on a monitor will always be 300x300 pixels and here it does not matter what dpi setting you have.
Make a test ina a image processing software and specify 300dpi and specify 1 dpi or 10, some programs do not allow 1 dpi but it does not matter and now view each image on your montior. Both will have the same size on you monitor.
Now take that same image and send it to a rpinter and you will be surprised :-)
[snip]
Well, you mean setting the printer to output at 300dpi. Indeed, grainy as f••k.
Anyway, ah yes, the classic confusion of PPI and DPI. (For those who don't know, PPI [pixels per inch] refers to the "logical" pixels in a digital image. DPI [dots per inch] refers to the physical dots in an output device used to create said pixels.) But yeah, DPI is what everyone uses to refer to both, and here, I chose to just go with it.
For historical context, the 300ppi rule of thumb for photos (at the
final output size, which marketing weenies don't understand) was basically because that's a good, sufficiently high resolution for the photos to exhibit no jaggies when sending them for offset printing at 2450dpi. (For line art, you really wanted scans at 1200ppi at the final output size, assuming you didn't have access to vector graphics.) Generally, for photos, you want the photo's PPI to be at least 1/10 of the DPI of the printer. So for 2450dpi offset, 245ppi would be enough, so 300ppi gives you an added margin of error. Some types of dithering (like the scatter dithering normally used on inkjets, but occasionally on offset as well) allow for greater sharpness, and so those can benefit a bit from even higher PPIs in the photos.