Some images are not extracted as viewable images

[pietermarsman]

Bug report

If an image encoding is not recognized the image is written as a .img file. But the pdf can show the images so the extracted images should also be viewable.

Example pdf: https://www.robots.ox.ac.uk/~vgg/publications/2012/parkhi12a/parkhi12a.pdf

Command:

pdf2txt.py example.pdf --output-dir cats-and-dogs

It extracts Im1.8.16x237.img which cannot be shown by an image viewer. Also all the bmp images seems to be broken.

Solution: detect more encodings and use those to write the images.