RGBA & affinity photo 2

[laurent32]

Hi all,

I've got a python warning telling me :

"UserWarning: Palette images with Transparency expressed in bytes should be converted to RGBA images"

when I use a png image with transparency in my routine.

How can I convert (export ?) my png file in order to bypass that warning message ?

Here is my source file :

Here is the file I get with my routine :

There is a problem, I lose my transparency (see green px)…

Thanks for your help.

[walt.farrell]

If you Open your PNG in Affinity Photo 2, what color format is shown in the Context Toolbar?

[laurent32]

Hi Walt,

 Here is what I've got with my original affinity file :

Here is what I get when I export to a png file with affinity :

And here is what I get if I open back in affinity photo 2 the file I get after using a python routine :

Is that the information you wanted ?

[walt.farrell]

Yes, thanks. But I have no idea what's going on. Sorry.

[GarryP]

28 minutes ago, laurent32 said:

And here is what I get if I open back in affinity photo 2 the file I get after using a python routine :

I think the important step here is “after using a python routine”.

We don’t know what the python routine needs, or what it is doing, or what it’s supposed to do, so we can’t know what it needs, or should change, or has changed.

If you can upload the python routine then a python expert may see it and give further advice, but without it we’re pretty much in the dark.

[laurent32]

Yes @GarryP, the problem might come from one of the packages I use in my .py routine (PIL)…

First I wanted to check if I was missing something evident in Affinity photo 2.

I'll send part of my routine in an upcoming post.

[laurent32]

This png file gives the problem :

While this one doesn't :

They both are png files with transparencies.

I really wonder why they are not treated the same way by my Python routine using the Pillow package for a simple resize ?

Can anyone tell me if there is a difference in the way those 2 files are built ? 

[NotMyFault]

The message says you have a palletized PNG file, and alpha channel. It seems that combination causes issues.
To correct, export from APh, but deselected palettierend in export settings. This will then create a regular RGBA image.

[laurent32]

Thanks for the idea @NotMyFault.

The problem is that I did not use the palletized option, I export with the standard png profile :

BUT your answer made me remember that i do use ImageOptim to get more compact files.

Here are my ImageOptim prefs :

ImageOptim could cause the problem then… ?

So… how could I work on the files that have the problem to revert back to a "normal" png file ?

Exporting a new png file, with "palettisé" untick does not correct the problem.

Thanks again for your help.

[NotMyFault]

The files from your first post in this thread differ.

the problematic blue one has a feathered edge on alpha channel, meaning alpha values with a gradient from 0.0 to 1.0

the ok green one has a hard edge with hard transition from 0 to 1.

I adjusted the blue one to have hard edge  too.

can you try if this solves the isse?

 

[NotMyFault]

1 hour ago, laurent32 said:

BUT your answer made me remember that i do use ImageOptim to get more compact files.

 

Well, in future try to go without this tool, or at least keep the original files and check both if they work to identify which app causes the issue.

[NotMyFault]

It could simply be a outdated python release. Search the web for the error message

 

https://github.com/EmilStenstrom/mybgg/issues/34

[laurent32]

44 minutes ago, NotMyFault said:

I adjusted the blue one to have hard edge  too.

can you try if this solves the isse?

Nice idea @NotMyFault, but…

I tried twice, the routine is still ok with the green one and NOT OK with the blue one…

There must be something different in that blue file… or in that green file ???

I mean other than what you just found (which is nice).

[laurent32]

I'm not sure, and I don't know if it could have an incidence…

But I think…

— I initially selected pixels and erased them to build my transparency for the problematic blue file.

— I initially used vector tool to build my transparency for the green working file.

I searched my disks and found my original blue file (jpg that I turned into a png with transparency) :

Can you turn that jpg file into a png with transparency ?

Maybe I'm doing something wrong ?

Maybe your png will work ok ?

[NotMyFault]

2 hours ago, laurent32 said:

Can you turn that jpg file into a png with transparency

1. Open jpeg in Affinity Photo
2. ensure „transparent canvas“ is active, to be able to  see transparency in canvas 
3. check image is of type pixel layer. If not, or in doubt, rasterize layer.
4. Use flood selection tool, activate detect edges, click on white background
5. Normally hitting delete key removes the white background
6. if this does not work, use erase brush, make it large and hard and 100% opacity, and swipe generously over image until all white is removed.
7. check with channels panel, activate alpha, to see if process is complete.
8. export as PNG

 

 

[laurent32]

1 hour ago, NotMyFault said:

1. Open jpeg in Affinity Photo
2. ensure „transparent canvas“ is active, to be able to  see transparency in canvas 
3. check image is of type pixel layer. If not, or in doubt, rasterize layer.
4. Use flood selection tool, activate detect edges, click on white background
5. Normally hitting delete key removes the white background
6. if this does not work, use erase brush, make it large and hard and 100% opacity, and swipe generously over image until all white is removed.
7. check with channels panel, activate alpha, to see if process is complete.
8. export as PNG

That's what I do, tried again, still have the problem so I guess I have to have a closer look at Python3 and Pillow…

Both of them have been updated not long ago…

Pillow might not be great in png manipulation ?

But then why is it good with my green file… a mystery…

If I find an answer I'll post it here…

Thanks @NotMyFault and all.

[R C-R]

11 hours ago, laurent32 said:

ImageOptim could cause the problem then… ?

I don't think so but maybe try it without lossy 'minification' enabled & see what happens. 

FWIW, I use ImageOptim without that enabled & this what I get for your image.jpeg.d8a6c627cc7e1ad4e4f93e9c201f79f1.jpeg file is this ~160 KB file.

What does you Python & Pillow stuff say about it?

[laurent32]

13 hours ago, R C-R said:

I don't think so but maybe try it without lossy 'minification' enabled & see what happens. 

FWIW, I use ImageOptim without that enabled & this what I get for your image.jpeg.d8a6c627cc7e1ad4e4f93e9c201f79f1.jpeg file is this ~160 KB file.

What does you Python & Pillow stuff say about it?

Great job @R C-R !! You identified the problem with my blue file !

And also I did some tuning on my Python3 code and everything seems to be back in order now !

Thanks all for your knowledge.