PPI after cropping and resizing images

[budjames]

After cropping a file from Canon 1DsMkII, converted from RAW using ARC 3.2, and resample check box uncheck, I often end up with PPI that contain fractions and that are not the usual 240, 360 etc. For instance, I might end up PS CS2 calculating a PPI of "302.575" after adjusting the image size under the Image/Image Size dialogue box.

Should I instead type in the PPI and let PS CS calculate the image size? Does the way I currently doing it compromise my output quality? (Usually printed to my Epson 2200).

Thanks.

Bud James
North Wales, PA

[mikeseb]

After cropping a file from Canon 1DsMkII, converted from RAW using ARC 3.2, and resample check box uncheck, I often end up with PPI that contain fractions and that are not the usual 240, 360 etc. For instance, I might end up PS CS2 calculating a PPI of "302.575" after adjusting the image size under the Image/Image Size dialogue box.

Should I instead type in the PPI and let PS CS calculate the image size? Does the way I currently doing it compromise my output quality? (Usually printed to my Epson 2200).

There is something to be said for arriving at the final output resolution in Photoshop rather than making your printer driver do it, as PS is likely to do a better job with whatever up- or downsampling is required.

Set your output resolution (I print via ImagePrint so I use 360ppi) and then check the "constrain proportions" (assuming you want the resized image proportions the same) and "Resample Image" checkboxes. Select "Bicubic Sharper" if you are downsampling. Then enter one of the dimensions for final print size; PS will calculate the other dimension, maintaining the image's proportions, and resize and resample to final output size and resolution. These parameters determine your final file size.

Others here will no doubt point out other options. Give this a try.

[Tim Gray]

I'm a big fan of Qimage - it totally bypasses the uprez/dpi issue.

[Mark D Segal]

I've made so many fine-looking prints on an Epson 4000 and 4800 (which print incredibly fine detail) at so many different sizes and PPI output resolution that I think this whole issue - within a wide range of specifications - is largely academic/pixel-peeping. The best answer to your question is that you should select a decent representative image - preferably one with some diagonals in it, and print it at the same size using different PPI settings (which means you leave the RESAMPLE IMAGE option in the Photoshop Image Size Dialogue box UNCHECKED). Then compare the prints WITHOUT a magnifying glass. Do it for any PPI setting between 240 and 480.

[budjames]

I've made so many fine-looking prints on an Epson 4000 and 4800 (which print incredibly fine detail) at so many different sizes and PPI output resolution that I think this whole issue - within a wide range of specifications - is largely academic/pixel-peeping. The best answer to your question is that you should select a decent representative image - preferably one with some diagonals in it, and print it at the same size using different PPI settings (which means you leave the RESAMPLE IMAGE option in the Photoshop Image Size Dialogue box UNCHECKED). Then compare the prints WITHOUT a magnifying glass. Do it for any PPI setting between 240 and 480.
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Mark, I always have resampling unchecked. I can't remember ever printing with it checked. My prints look great even though after cropping to 11x14 in PS CS2 and ending up with odd PPI values with fractions. Typically, the PPI is about 302 after cropping the image to 11 x 14. The prints look great when them come out of my Epson 2200. I usually flatten the PS files to a 16 bit TIFF and print using ImagePrint 6.0 RIP.

I'll do a few tests like you suggested to see if I can notice any difference.

Thanks.

Bud James