How would you approach reading jpg files and scaling them in zig?

[short narwhal]

How do people process jpg files in zig right now? I know zbout zigimg but I need to do things like

• detect the image camera rotation and fix the image rotation.
• scale the image down if it is too large.

Would you link to a c library? Or is some combination of zigimg with some other libraries possible?

[short narwhal]

Although this doesnt seem to support exif data, or a basic simple image crop, this seems like a partial solution:

https://github.com/zig-gamedev/zstbi

[hoary compass]

Analizing camera angles is a hard problem to solve on it’s own, I believe you should do some research about image processing, find some papers. Of the top of my head, using the FFT might give you some insights.

[short narwhal]

The camera roation is usually inside the EXIF header. Its just a matter of reading the exif data (which zigimg doesnt support unfortunately)

[hoary compass]

How does the camera knows how much it has rotated ? Is there a sensor inside ?

[short narwhal]

Yes, its reasonably common for modern cameras to want to save processing power. They store the image bytes from left to right , top to bottom from directly from the sesor, and then if the camera was sideways or upside down, stuff a rotation number in the exif header.

This saves hardware (or software) having to reverse or flip all the bytes if the camera is upside down.