How to convert BGRA to RGB bitmap?

[Dmitry Grebenyuk]

Hi,

I use `ash::image_util::DecodeImageFile()` which returns `gfx::ImageSkia` with kBGRA_8888_SkColorType.

I have two ML models. For one I feed .bitmap() and it works. For another, I need to make a mapped region with RGB color type. How can I do it?

-Dmitry

[Jeremy Roman]

You can use SkBitmap::readPixels to copy to an SkPixmap of the structure you want, in memory you allocate; this should be able to do the color type conversion you want. If you need something more complicated, you can use an SkCanvas backed by memory and draw the image into that.

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[Dmitry Grebenyuk]

Thanks,

Is there a more optimized method without looping over each pixel?

[Avi Drissman]

I'd second Jeremy's suggestion to make a new canvas with the pixel order you want, and draw the source image into it. Skia is optimized, and this would let your code take advantage of any optimization that Skia has or will have implemented.

Avi

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[Jeremy Roman]

SkBitmap::readPixels will do the entire pixmap, not an individual pixel. I believe it does use SIMD optimizations, but haven't dug under the hood.

Making a canvas and drawing into it is more general, and should also be reasonably optimized.