ImageReader::open and write_to performance issue about image HOT 8 CLOSED

To start with it would help to know which image format(s) you're dealing with. But even that isn't much to go on. Many of our encoders/decoders are thousands of lines of code and have already had a significant amount of optimization. In some cases they are slow primarily just due to the complexity of the format

The most actionable things would probably be providing specific image files that decode much faster with other libraries or profiling data identifying particular slow sections that could be improved

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Make sure you are compiling in release mode / with optimizations. Beyond that, this issue really isn't actionable without a lot more detail

PR's for specific optimizations are of course welcome!

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Which details are needed?

However, I compile my application in release mode (optimization 3).

I will try to inspect code...

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I always encode in PNG (output format, which then is encoded in base64 to be printed in html). I wanted to encode in AVIF (I need a transparent background format), but it is not out-of-the-box format...

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The PNG encoder is already heavily optimized. AVIF as well, but you'll want to enable the nasm feature for best performance

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Thank you, but, then I don't know how open and write_to are so a time consuming tasks...

Anyway, how can I use AVIF and what is nasm feature?

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The functions are time consuming because they do a lot of work. Just because each step is efficient doesn't mean it still won't take a while to complete.

You can encode to AVIF the same way you're currently doing for PNG, just change the file extension or pass ImageFormat::Avif as applicable. The nasm feature enables the asm feature on rav1e which you can read about in their readme

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Thank you, I will try it!

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