PPI for web output

digital paradise

I am confused. I have been told that PPI resolution as nothing to with screen resolution yet Jeff Schewe states here that you should set it to 72 -120 in LR in this forum.

http://www.luminous-landscape.com/forum/index.php?topic=66916.0

We were having a lengthly discussion on LR output sharpening at POTN and this topic came up as well. Through some searches I came across Digital Grin and I realized Andrew responded to that thread.

This video (start at minute 8) states that PPI has nothing to do with screen resolution.

http://www.youtube.com/watch?v=44mV3NsLmXw&feature=relmfu

arodney

The reason Jeff is stating the 72-120 range is that LR will use that info for screen sharpening. Sharpening is resolution dependant. For this automatic sharpening to exist, LR needs some range to apply the sharpening.

In Deke’s presentation, he’s setting the pixel dimensions for his video based on HIS display (1700 or something). Fine. If you take that image onto my 30” display, it’s size depends on how I’m driving the display (2500x1600, 1900x1200 etc). The same document will be a different size on that display from the same pixels depending on the resolution of that display. So the same PPI in Deke’s image will be a different size on my display depending on how it is set.

digital paradise

Thanks for the answer. This discussion was going on at POTN and got this answer which matches yours.

Don't confuse two different subjects here. The ppi (or dpi) tag in a rendered file's metadata has absolutely no effect on the way that image is displayed on a monitor. It will always be displayed at the monitor's ppi, because the monitor can do no other. But that is not what Schewe is talking about. He is talking about the Output Sharpening done by LR and simply saying that in order to work at its best the tool needs to have a number between 72 and 120 entered in that box when the image is downsized for posting and Screen Sharpening is requested. It is only about getting the best sharpening and has nothing to do with display size. IOW, if you are resampling to 1080x1920 pixels to fill a HD screen, set 100 ppi, but if you want a 3.6 x 6.4 print, set 300.

arodney

What is POTN?

digital paradise

http://photography-on-the.net/forum/

All camera manufacturers are welcome there.