smartcrop with 90/270 rotation: bad extract area

[ralrom]

It seems that rotating an image before cropping it causes a bad extract area error. This is possibly related to #1134

Here is the minimal breaking setup

[lovell]

Thanks, I've been able to reproduce this problem.

The input image appears to have an EXIF orientation value of 256, which falls outside the 0-8 validity range. This invalid orientation value is clipped to 8, which will result in a 270 degree rotation to "correct". This means even if it were to work, the output might not be what you'd expect.

Broken metadata aside, there's still an underlying problem. Here's a minimal test case that ignores the EXIF orientation but still fails with the smartcrop: bad extract area error in sharp v0.20.0.

// https://raw.githubusercontent.com/ralrom/sharp-bug-repro/master/images/apocalypse.jpg
sharp('apocalypse.jpg') // 1024x1034
  .rotate(270)
  .resize(256)
  .crop(sharp.strategy.entropy)
  .toFile('breaks.jpg', console.log);

[lovell]

The underlying problem here was that both dimensions had suffered a cumulative rounding error, one above the target dimensions and the other below.

It's an edge case so thank you for taking the time to report it with a reproducible test case.

Commit f60f7da adds these dimensions as a unit test and provides the fix to clamp values before attempting the smartcrop operation. This will be in v0.20.1.

[lovell]

v0.20.1 now available, thank you for reporting this problem.