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9248 :: Show Nim: Pure Nim .jpeg decoder in Pixie

• treeform (orginal) [2022-06-20T00:00:19+02:00] view original

  Hey all, I wanted to post about the new 100% Nim JPEG decoder in Pixie.

  JPEG is a super common image format but loading .jpeg files in Nim has required bindings to other libraries like stb_image. Even though stb_image is awesome, we wanted to be able to do this directly in Nim.

  It turns out .jpeg files are very complicated to decode but in the end we won. Pixie can now decode color and grayscale .jpeg files, including progressive .jpegs and all sorts of other various flavors.

  Using Pixie to load a .jpeg is super simple:

  let image = readImage("cat.jpg")
  Run

  After loading the image you can use all of the other features Pixie offers, such as paths, maksing, text, etc. Also, since Pixie gives you an RGBA buffer, you can send that data to the GPU for games.

  We made a quick video highlighting the new feature here: https://www.youtube.com/watch?v=bqB8oPeSx_o

  We are going to record a technical discussion very soon so I'll reply here again when we have that recorded.

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• demotomohiro (orginal) [2022-06-20T01:39:27+02:00] view original

  It would be better if there is the link to Pixie repository for people don't know about Pixie: https://github.com/treeform/pixie

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• guzba (orginal) [2022-06-20T01:43:08+02:00] view original

  Funny how such a simple thing can be completely overlooked. Thanks!

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• elcritch (orginal) [2022-06-20T03:22:54+02:00] view original

  This is really cool! Your graphics work is just awesome. :-)

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• PMunch (orginal) [2022-06-20T08:06:12+02:00] view original

  Does this being implemented in pure Nim mean that we can read JPEGs on compile-time? I wanted to be able to read some image format in order to code it directly into an Arduino program, and I ended up implementing my own BMP reader.

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• guzba (orginal) [2022-06-20T08:31:54+02:00] view original

  No, sorry to say but compile time decoding will not work. I fear it would also be glacially slow given how much processing JPEG decoding requires (inverse discrete cosine transforms, YCbCr -> RGB, single-channel buffer up-sampling, Huffman bitstream decoding).

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• dom96 (orginal) [2022-06-20T16:18:51+02:00] view original

  You can always build a binary which reads JPEGs and outputs them in a format that you can then read at compile-time. That way you'll get the same functionality.

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• treeform (orginal) [2022-06-20T16:32:48+02:00] view original

  Here is the technical discussion we mentioned before: https://www.youtube.com/watch?v=vYwD7OynFcg

  We talk about:

  • JPEG format
  • STB
  • How clever JPEG is
  • How strange the binary format is
  • Progressive JPEGs
  • Restart Markers
  • Testing and Fuzzing

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