I have a background layer and am inserting a 512x512 image.

enter image description here

I want to set the inserted image to 512 x 512. I use ctrl + t and make it 512x512 and apply the free transform.

enter image description here

If I push ctrl + t again to check that it applied it shows it at 508.74 x 508.74. Why does it not like the size 512 x 512 when that is the imported images actual size?

  • Probably because the source says the conversion factors to physical units is different than what Photoshop thinks. Photoshop tires to retain physical size not pixels.
    – joojaa
    Jun 28, 2016 at 12:46
  • @joojaa Is there a way to override this? Seems odd that it would change an explicitly set resolution.
    – Striar
    Jun 28, 2016 at 12:48
  • Curious, what is the document dimensions?
    – ErickP
    Jun 28, 2016 at 16:37
  • @ErickP It is 8192 x 4096. I'm assembling a moon sphere map so I need all the pieces to fit perfectly. The temporary work around is to open the images into a 512x512 canvas and then resize it.
    – Striar
    Jun 29, 2016 at 12:15

2 Answers 2


I've encounter this when I try to change the dimensions as you did. I realized that if I kept the "maintain aspect ratio" on while entering the pixel dimensions it would tend to round it off a pixel or two. Not sure why. BUT if I entered the number manually for both the (H) and (W) then it would keep what I entered. Give it a go and let me know if that works?


Only thing I can think of to explain why are differences of DPI between the two documents. Anyway, try this as a workaround: Open the first 512x512 image and float the background (convert it to layer 0) and Save As a new PSD. Now go to Image > Canvas size, click the top-left alignment square and change the resolution (not the DPI!) to the final size you want. Now simply drag the other images in and position.

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