Downscaling in linear color space? about fast_image_resize HOT 5 CLOSED

In version 2.0.0 I added PixelComponentMapper structure that allows you to create colorspace converters for images whose pixels based on u8 and u16 components.

Source and destination images for mapper may have different bit depth of one pixel component. But count of components must be equal. For example, you may convert U8x3 image with sRGB colorspace into U16x3 image with linear colorspace.

In addition, the crate contains functions create_gamma_22_mapper() and create_srgb_mapper() to create instance of PixelComponentMapper that converts images from sRGB or gamma 2.2 into linear colorspace and back.

You may use PixelComponentMapper to convert image colorspace before and after resizing.

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The current implementation does nothing special with pixel components and knows nothing about color space of image.

The main feature of this crate is the use of SIMD instructions of CPU to speed up image resizing. So it is most likely not possible to simply use closures for pixel transforming. Because this will significantly slow down the resizing.

I'll can try to add support of images with u16 components of pixel (U16, U16x3 and U16x4). But I don't promise that I will do it soon.

from fast_image_resize.

It doesn't need to be closures. It can be something based on macros so users can have compile-time optimized paths for common encodings like sRGB or Adobe RGB.

Without this the the crate is useless for downscaling u8 component images that are non-linear (100% of u8 component images that are photos, textures etc., for obvious reasons) since the results will be wrong.

I would put a note in the README at least.

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I've added support of U16x3 pixels. For now without optimizations using SIMD.

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v0.8.0

• Added optimisation for convolution of U16x3 images with helps of SSE4.1 and AVX2 instructions.

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