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Pixelated image after changing canvas size in Photoshop

#1
- I opened a PNG file which has some transparency and is 401x82 px.
- I wanted to add empty space above and below, to get the width/height ratio I wanted.
- I used Image > Canvas Size to change the image size to 401x111 px.
- This worked, and it extended the transparent background.
- As far as I understand, this should not stretch or affect the image content itself (or pixelate it).
- I saved as PNG, using defaults.
- It came out more pixelated than the original. I'm viewing it at the same size as the original.

I'm using Adobe Photoshop CS5 v12.
 

Eggy

Forum Moderator
Staff member
Forum Moderator
#4
Let us try some possibilities:
- open your image
- duplicate it (ctrl+J) and make the top layer active
- make it a smart object
- click away the eyeball from the original picture (bottom layer)
- apply the canvas size changes to the smart object top layer and see how that turns out.
- if there's no pixelation rasterize the top layer and see if something changes
 
#5
In my older version of PS, I don't see how to make something a smart object. But I OPENED the file as a smart object, using menu "File > Open as Smart Object". I applied the canvas size change, saved as PNG, and it still looks bad. So I didn't do what you said with layers. Is that ok?

On another note, the original file was an 8 bpp PNG file. I'm saving it as 24 bpp. Is this an issue?

Also note that the above screenshot is of the original and saved files, opened in Irfanview, not in PS.
 

IamSam

Administrator
Staff member
Administrator
#7
Hello,
In my older version of PS, I don't see how to make something a smart object.
Right click on the layer (in the layers panel) and choose "convert to smart object".

On another note, the original file was an 8 bpp PNG file. I'm saving it as 24 bpp. Is this an issue?
Possibly.

As you have already stated and described, what your doing should not alter, stretch, or affect the image layer. So there is something else going on. We really do need the original PNG to test with.
 
#8
The problem seems to have nothing to do with me resizing the canvas size. It must have been something to do with saving the PNG. The source was 8 bpp. I saved it in both 8bpp and 24bpp, both produced the problem. I'll mention again that I have CS5, an older version of PS. I provided the source file to someone else, and he had no problem making the change in his newer version of PS. He sent me the output file, and I will use that. So I think it makes sense not to proceed with this investigation, but thank you for your help.
 

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