P: Document Size changes after creation

[Lelin Penheiro]

Dear Adobe Concerns,

I am an Adobe user since 1994. Recently, I am having a problem regarding document/image size issues which I have never faced earlier or I have never recognized it. I already talked with two college professors who are specially teaching on Adobe Softwares if they can help me out of this problem but unfortunately they failed to resolved the issues and they never recognized this issue too.

Actually, I have opened a document sized 45mm x 45mm with 300 ppi for one of my client. After opened the document, when I am checking the image size under the "Image" menu, it's showing 44.96 x 44.96 instead of 45 x 45mm, and for this reason, I failed to upload that image to a perticular website as they were asking for the file size 45 x 45mm. Can anyone tell me why the image size is showing different then the size I opened the document.

Thanks, Lelin Penheiro

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[CoryShubert]

Hi @Lelin Penheiro, we will be happy to have our team look further into this. A workround would be to increase the PPI to 302 which will make the file size 45mm x 45mm. In our testing this has been the same since CS6, so this is not a new issue.

Thank you,

[davescm]

Photoshop works in whole pixels. There are no half pixels or part pixels. At 300ppi 45mm equates to 531.496 pixels. So using 531 pixels equates to 44.96 mm or using 532 equates to 45.04mm 

Dave

[Pete.Green]

Hi @Lelin Penheiro ,

Thanks for the report on this, and you're right, this math can be confusing. @davescm is correct here that since images in Photoshop are comprised of pixels (raster), at this resolution of 300 dpi, the image at ~45mm will be 531x531 pixels.

If you were to increase the WxH by one pixel to 532x532 pixels at 300dpi, the resulting measurement would be 45.04mm x 45.04mm.

In order to realize 45x45mm at 300dpi, we would require a partial pixel since at 300dpi a single pixel is .08mm. 

Another way to work around this would be to adjust your DPI to 302, and you can realize the 45mm measurement (resulting in 535x535px).

Hopefully either of those solutions will work for your purposes. 

Regards,

Pete

[thedigitaldog]

Work in pixels (and yes, there are only whole pixels). 

If I make a new document in Photoshop, 45mm x 45mm @ 300 PPI I get 531x531 pixels. And in Image Size, I'm told that is 44.96 mm. Because 45 mm at 300PPI can't produce an exact size at that 300PPI value. If I use Pixels per CM, still no go; that's 118.11. Again, working in pixels solves this complication.