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I just ran into an interesting imageScaleToFit bug. I was writing some code to handle scaling an uploaded image when I got this error:
For gray scale images the interpolation argument must be one of: NEAREST | BILINEAR | BICUBIC | HIGHESTQUALITY | HIGHQUALITY | MEDIUMQUALITY | HIGHESTPERFORMANCE | HIGHPERFORMANCE | MEDIUMPERFORMANCE
According to the docs, the default interpolation is highestQuality so I don't quite get what CF is thinking I'm using. Specifying the interpolation made the error go away of course and then works just fine for grayscale or non-grayscale images. (I filed a bug report for this already.)