72 to 300 and back again?

[taygull]

OK,

When processing my photo's from RAW or JPEG, the default is 72dpi. If I convert the RAW image to TIFF or JPEG and save it on my hard drive do I lose anything at saving it at 72 dpi and then later converting it to 300 dpi if I want to print them?

I know I don't want to do multiple saves on a JPEG, I'm just wondering if I save at 72 dpi to keep the file "smaller" and then later convert to 300 dpi does it do anything bad to the image?

[jfrancho]

The dpi tag in raw will do nothing to file size.

[Curtis N]

Why do you care about DPI at all?
Be sure to read this thread (http://photography-on-the.net/forum/showthread.php?t=83445).

[taygull]

I've read the articles and I guess it is something that has to "sink" in, what I am concerend about is if I do all my post work and save the images at a "72" resoluiton then I later want to go back and send them to the printer to have them printed do I give up anything by changing the resolution to 300?

[taygull]

.....since we are on the subject how do you set up an online store for you photo's not knowing if the customer wants an 8"x10", 5"x7", 4"x6" or heck even a 20"x30"? What if you don't want to lose any of the "crop"?

[jfrancho]

Do the crops yourself, and only offer prints sizes that match the aspect ratio. If you want to print in an aspect ratio other than 2:3, you're out of luck, you'll have to crop.

[taygull]

OK...stupid question...is there a chart or grid that shows the aspect ratio to "inches"...so if I do a 10"x15" then the next down or up sizes will be ????? without a re-crop?

[DavidW]

10 x 15 is 2:3 aspect ratio. It's simple mathematics. Your DSLR is 3:2 native (or 2:3 in portrait!). Anything that isn't in the ratio 3:2 (for example, 10 x 8, which is 5:4, or 7 x 5 which is 7:5) is going to need a crop.


I've taken to creating and storing crops in my Photoshop files using paths. I use the rectangular marquee in the appropriate aspect ratio (set Fixed Aspect Ratio and input the ratio). When I'm happy with the crop, I go to the Paths palette, click the button to Make Work Path From Selection, then Alt (Option on the Mac) and drag the work path down to the New Path button so that I can name the path. For example, I may call a path "7:5 crop" or "A crop" (which is for A series paper - sqrt(2):1 aspect ratio).

When I want to crop to one of my stored crops, I hit the New button in the History palette so as not to inadvertently save over the top of the uncropped file, click the relevant path in the Paths palette, click the Load Path As A Selection button at the bottom of the Paths Palette, then Image -> Crop.


To adjust the dpi figure stored in the file - not that it usually makes any difference, go to Image -> Image Size..., and uncheck Resample Image. At that point, you can adjust the resolution. The other two figures will update accordingly. Press OK.



David