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Add support for reading DPI information from JPEG2000 images #5568

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merged 8 commits into from
Aug 2, 2021
Merged

Add support for reading DPI information from JPEG2000 images #5568

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7f275c1
Create BoxReader helper class to parse JPEG2000 header
rogermb Jun 30, 2021
5f4653d
Attempt to read dpi information from JPEG2000's resc header box
rogermb Jun 30, 2021
ae54838
If DPI is invalid, ignore it instead of raising an error
radarhere Aug 1, 2021
3ee5a9b
Stop reading from "res " after all information is extracted
radarhere Aug 1, 2021
0c600f1
Prevent reading past end of file pointer even if box length allows it
radarhere Jul 25, 2021
8828080
Removed unreachable code
radarhere Aug 1, 2021
8045ecc
Added tests
radarhere Aug 1, 2021
dab5721
Favour integer operations when calculating DPI
radarhere Aug 2, 2021
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3 changes: 0 additions & 3 deletions src/PIL/Jpeg2KImagePlugin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -154,9 +154,6 @@ def _parse_jp2_header(fp):
if reader.read_fields(">4s")[0] == b"jpx ":
mimetype = "image/jpx"

if header is None:
raise SyntaxError("Could not find JP2 header")
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@rogermb rogermb Aug 1, 2021 •
edited

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You're right, this is unreachable, reader.has_next_box() will never return False (because reader = BoxReader(fp) is initialized without a length), so the only possible outcome for a malformed image not containing a "jp2h" header is that reader.next_box_type() will eventually fail with some kind of exception.

While not exactly elegant, that's definitely better than having an if statement that misleads the reader. 👍


size = None
mode = None
bpc = None
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