Issue #853: Extract 4-bits images from PDF

[sheldonldev]

Pull request

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How Has This Been Tested?

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Checklist

• I have read CONTRIBUTING.md.
• I have added a concise human-readable description of the change to CHANGELOG.md.
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[pettzilla1]

CV2 requires GTK which is a copy left package this contradicts the licence which pdfminer.six uses and would heavily restrict pdfminer.six's uses , It is not recommended to merge this in its current format. It would in addition fall foul of new requirements in pull request #819 which is currently waiting to be merged. please insure packages used have no copyleft dependencies

[pettzilla1]

Please remove the usage of copy left dependent packages , CV2 requires such packages and should make pdfminer copy left

[pietermarsman]

@sheldonldev Thanks for your contribution and time!

@pettzilla1 Thanks for being strict on the licenses!

Not accepting this because of the copy left licence it requires. For more information, see the CONTRIBUTING.md.