Should the ppi be changed prior to uploading?

Rohirrim · June 6, 2005

Post Deleted- sorry, but I was able to find the answer after more searching

jfriend · June 6, 2005

Why even pay attention to dpi?

Rohirrim wrote:

I'm having a little trouble understanding when to change ppi.

When I open images in Photoshop from my Digital Rebel (taken at the highest jpeg setting) they open up at 180 ppi. This seems low as a default, but I can't figure out how to change it, or even if I should. Is this setting a camera default? Should I change the ppi prior to uploading to smugmug if I want to order prints?

Thanks for any advice,
Steve

I know there are different opinions on this subject, but I NEVER change PPI for any images and I'm a bit surprised that so many people think it's important to actually change that value. On the image itself, this number is a made up value and has no meaning by itself. The camera puts the number into the initial image and it really has NO idea what the ppi is because it's only meaningful if you take a specific number of pixels and match it with a specific output size. The ONLY thing that really matters is how many pixels per inch you will have when you print a specific size and the camera doesn't know that.

The reason that I don't care what the image is set to is that I never print an image at it's native resolution. Anytime I print an image, I take the highest resolution source image I have and I tell my printing software what printed size I want and let my software scale it in the process of printing. That's what Costco will do, Wal-Mart will do, Smugmug will do, Ofoto will do, etc... So, that's what I do when I use any of those services or if I print it myself.

The ONLY thing that really matters in my workflow is whether you have enough pixels in your image for the size you are printing. In that case, I try to make sure I have at least 220 pixels per inch of printed area. I don't try to convert my image to 220 dpi, I just do a check to make sure I have at least that so I'm aware of whether my printing software has enough pixels to do a decent job. If you don't have enough pixels either because the source image was small or the printed size is huge, you will suffer some degradation and the software will do it's best to interpolate (make up pixels) as a substitute, but there will be a degradation.

So, all I think about in terms of dpi is to ignore it completely until you go to print a specific size greater than 8x10, assuming that my photo workflow generally has more than enough pixels for a good 8x10 so just let me printing software handle it. If I'm printing a size larger than 8x10 (or in a few cases, I know I'm printing an extreme crop), I will check to see what the resulting ppi will be at my large size. I'm only doing the check to decide if I still want to proceed with the large print. If I found I'd only have 72 dpi at my large size, I probably wouldn't do the large print, but if it came out to 180 dpi, I'd likely proceed anyway and just know it wouldn't be quite as good as I'd like it to be because there aren't enough source pixels.

--John

Rohirrim · June 6, 2005

Thanks for the additional info (nt)
Thanks for the additional info (nt)

Should the ppi be changed prior to uploading?

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