Photoshop 6.0/Windows XP and PPI

AH
Posted By
alisha_hess
May 14, 2005
Views
295
Replies
1
Status
Closed
I’ve been reading down through all the topics concerning DPI and/or PPI and I haven’t found anything that helps with my problem. I have been designing using photoshop 6.0 and have recently put my creations up for sale on an online store. The store’s requirements are for all files to be saved as jpg’s or png’s and they must open up at 300ppi and in actual size. When I save in jpg format, my files reopen in the exact ppi I started at. However, when I save in png format, my files always reopen at 72 ppi. To give you a picture of what’s happening, I’ll walk you through my steps. I go to File, and New. I set the image size at 1 inchx 1 inch and 300 pixels/inch. I add text or whatever else and when I am finished, I go to File, and Save as and save the file. Then if I open the file up again, and recheck image size, it is now set at 4.167 inches by 4.167 inches and at 72 pixels/inch. Now, the width and height of the file is essentially the same because the pixel demensions stay the same: at 300x300pixels. If I reset the p/i back to 300, my file converts back to the 1inch by 1inch I started with. My questions is, how to I get the file to actually open at 300ppi instead of coverting back to the 72ppi everytime? Is this a photoshop issue or a windows(I have windows xp)issue, or neither? And how do I go about fixing it so I can meet my requirements? Thank you in advance for any advice!

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MD
Michael_D_Sullivan
May 14, 2005
It looks like Photoshop is recording 72 dpi as a default resolution of a PNG for some reason, even though the PNG specification specifically provides for recording the actual image resolution per meter. I saved an 8×10" PNG at 300 dpi, and both Bridge and Photoshop’s File Info report it as being 2400 x 3000 pixels (correct) and 72 dpi (incorrect). Interestingly, when I open the picture in PSCS2 it displays at the right size (actually Image>Image Size reports it as 299.999 ppi), and Windows Explorer reports its resolution in the properties panel as 299 ppi.

This looks like a bug in how Photoshop records (or doesn’t record) the proper data in the PNG information fields (specifically the pHYs chunk, per Section 4.2.5 of the PNG spec).

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Learn how to optimize Photoshop for maximum speed, troubleshoot common issues, and keep your projects organized so that you can work faster than ever before!

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