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fix: Use image/jpeg as MIME type for canvas.toBlob#801
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mloenow wants to merge 1 commit intomicrosoft:masterfrom
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fix: Use image/jpeg as MIME type for canvas.toBlob#801mloenow wants to merge 1 commit intomicrosoft:masterfrom
mloenow wants to merge 1 commit intomicrosoft:masterfrom
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The default MIME type for `canvas.toBlob(..)` is `image/png`[0], however, when exporting video assets (e.g. to the Pascal VOC format), the file extension is `.jpg` for each frame, resulting in a mismatch between extension and MIME type, which can cause issues in your data pipeline. Verified with `PIL` (`image = PIL.Image.open(encoded_image_io)`, `image.format`), and `exiftool` below: ``` $ exiftool /data/Test-PascalVOC-export/JPEGImages/IMG_4926.MOV#t=0.066667.jpg ExifTool Version Number : 11.30 File Name : IMG_4926.MOV#t=0.066667.jpg Directory : /data/Test-PascalVOC-export/JPEGImages File Size : 2.5 MB File Modification Date/Time : 2019:05:03 16:35:29+02:00 File Access Date/Time : 2019:05:03 18:19:43+02:00 File Inode Change Date/Time : 2019:05:03 16:35:29+02:00 File Permissions : rw-r--r-- File Type : PNG File Type Extension : png MIME Type : image/png Image Width : 1080 Image Height : 1440 Bit Depth : 8 Color Type : RGB with Alpha Compression : Deflate/Inflate Filter : Adaptive Interlace : Noninterlaced Image Size : 1080x1440 Megapixels : 1.6 ``` This pull request explicitly sets the MIME type to `image/jpeg` with full quality (1.0). [0] https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement/toBlob#Parameters
Codecov Report
@@ Coverage Diff @@
## master #801 +/- ##
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Coverage 87.9% 87.9%
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Files 129 129
Lines 4845 4845
Branches 922 922
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Hits 4259 4259
Misses 584 584
Partials 2 2
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wbreza
approved these changes
Aug 2, 2019
| const ctx = canvas.getContext("2d"); | ||
| ctx.drawImage(video, 0, 0, canvas.width, canvas.height); | ||
| canvas.toBlob(resolve); | ||
| canvas.toBlob(resolve, "image/jpeg", 1.0); |
wbreza
suggested changes
Aug 2, 2019
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Please re-target to the develop branch. Thanks!
mloenow
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Aug 6, 2019
Retargeted. See microsoft#801. Closes microsoft#801, microsoft#838.
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The default MIME type for
canvas.toBlob(..)isimage/png[0], however, when exporting video assets (e.g. to the Pascal VOC format), the file extension is.jpgfor each frame, resulting in a mismatch between extension and MIME type, which can cause issues in your data pipeline.Verified with
PIL(image = PIL.Image.open(encoded_image_io),image.format), andexiftoolbelow:This pull request explicitly sets the MIME type to
image/jpegwith full quality (1.0).[0] https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement/toBlob#Parameters