Different behavior of fitz.Pixmap() between PyMuPDF 1.23.8 and 1.23.15

[dothinking]

With upgrading PyMuPDF from 1.23.8 to 1.23.15, fitz.Pixmap() doesn't work as expected. Do I miss something, or if it's an upstream issue.

sample.pdf

PyMuPdf 1.23.8

>>> import fitz
>>> fitz.version
('1.23.8', '1.23.7', '20231219000001')
>>> doc = fitz.Document('sample.pdf')
>>> doc[0].get_images(full=True)
[(17, 0, 1731, 1331, 8, 'DeviceCMYK', '', 'Im0', 'DCTDecode', 0)]
>>> pix = fitz.Pixmap(doc, 17)
>>> pix.colorspace
Colorspace(CS_CMYK) - DeviceCMYK
>>> pix = fitz.Pixmap(fitz.csRGB, pix)
>>> pix.save('sample-1.png')                      <- perfect

PyMuPdf 1.23.15

>>> import fitz
>>> fitz.version
('1.23.15', '1.23.9', '20240116000001')
>>> doc = fitz.Document('sample.pdf')
>>> doc[0].get_images(full=True)
[(17, 0, 1731, 1331, 8, 'DeviceCMYK', '', 'Im0', 'DCTDecode', 0)]    <- color space = DeviceCMYK
>>> pix = fitz.Pixmap(doc, 17)
>>> pix.colorspace
Colorspace(CS_RGB) - DeviceRGB                     <- color space seems changed to DeviceRGB
>>> pix = fitz.Pixmap(fitz.csRGB, pix)
>>> pix.save('sample-2.png')                   <- the png color is different from the source

[JorjMcKie]

Thanks for posting this. Looking now.
Background:
The difference between these PyMuPDF versions is that since 1.23.9 we are an "rebased" architecture. At 1.23.8, import fitz pointed to the "classic" implementation.
Now, import fitz points to the "rebased" implementation and the classic one is available via import fitz_old as fitz.
Let me check / confirm your observation. We will possibly make an issue from your post.

[JorjMcKie]

@dothinking - confirming your observation:
The Pixmap made from the image is indeed converted to RGB but shouldn't: it should be CMYK.
Converting to a bug.

[dothinking]

Thanks for your quick reply. Then I should downgrade for now and waiting for a fix.

[julian-smith-artifex-com]

This is fixed in release 1.23.16.