This commit fixes a pair of errors related to saving images as JPEG. In the first case, it addresses an error whereby a 16 bit TIFF would raise an OSError when trying to save as JPEG, owing to JPEG's 8 bit limitation.
In the second case, it addresses an error whereby the image is palette based, and the image won't convert to JPEG.
In both cases the fix is to convert with RGB so the JPEG can generate.
The solution here is more general in that grayscale images that have an alpha channel will have that removed, and anything that isn't grayscale or RGB will be converted to RGB.
Functionally grayscale RGB images with the same color on each channel will be converted to grayscale also.
The 16 bit error is as follows:
Traceback (most recent call last):
File "/usr/local/bin/hocr-to-epub", line 672, in
EpubGenerator(args.infile, args.metafile, args.imagestack, args.scandata, args.outfile, use_kakadu=args.kakadu)
File "/usr/local/bin/hocr-to-epub", line 291, in __init__
self.generate()
File "/usr/local/bin/hocr-to-epub", line 590, in generate
cropped_image_filename = self.img_stack.crop_image(page_idx, box)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/bin/hocr-to-epub", line 132, in crop_image
region.save(output_filename)
File "/usr/local/lib/python3.12/site-packages/PIL/Image.py", line 2568, in save
save_handler(self, fp, filename)
File "/usr/local/lib/python3.12/site-packages/PIL/JpegImagePlugin.py", line 642, in _save
raise OSError(msg) from e
OSError: cannot write mode I;16 as JPEG
Traceback (most recent call last):
File "/usr/local/bin/hocr-to-epub", line 684, in
EpubGenerator(args.infile, args.metafile, args.imagestack, args.scandata, args.outfile, use_kakadu=args.kakadu)
File "/usr/local/bin/hocr-to-epub", line 294, in __init__
self.generate()
File "/usr/local/bin/hocr-to-epub", line 602, in generate
cropped_image_filename = self.img_stack.crop_image(page_idx, box)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/bin/hocr-to-epub", line 135, in crop_image
region.save(output_filename)
File "/usr/local/lib/python3.12/site-packages/PIL/Image.py", line 2568, in save
save_handler(self, fp, filename)
File "/usr/local/lib/python3.12/site-packages/PIL/JpegImagePlugin.py", line 642, in _save
raise OSError(msg) from e
OSError: cannot write mode P as JPEG
This commit fixes a pair of errors related to saving images as
JPEG. In the first case, it addresses an error whereby a 16 bitTIFFwould raise anOSErrorwhen trying to save asJPEG, owing toJPEG's 8 bit limitation.In the second case, it addresses an error whereby the image is palette based, and the image won't convert to
JPEG.In both cases the fix is to convert with
RGBso theJPEGcan generate.The solution here is more general in that grayscale images that have an alpha channel will have that removed, and anything that isn't grayscale or RGB will be converted to RGB.
Functionally grayscale RGB images with the same color on each channel will be converted to grayscale also.
The 16 bit error is as follows:
Sample item: https://archive.org/download/ColibriesdeMexi00Ariz
The palette error is as follows:
Sample item: https://archive.org/download/jiltandothersto00readgoog