Accept raw buffer as input

[mikemorris]

For reading pixels from the GPU and then compressing to PNG or JPEG.

Error: Input buffer contains unsupported image formatVipsForeignLoad: buffer is not in a known format

[mikemorris]

It looks like this should be supported upstream by vips_image_new_from_memory, but may not be detected/implemented because of the differing naming convention from vips_image_new_from_buffer. My local libvips-8.0.2 installed via Homebrew reports raw file input/output support when I add "raw" to https://github.com/lovell/sharp/blob/master/src/utilities.cc#L99 and remove the manual raw support description.

[lovell]

Yes, it should be quite easy to add this, thanks for the suggestion.

We'd need to work out a way for a user to provide the width, height and number of channels alongside the Buffer containing raw data, either as a second parameter to the constructor or via a new method.

This feature would probably have to assume, at least initially, that the raw data is 8 bits per pixel, with 1x channel for greyscale, 2x channel for greyscale+alpha, 3x channel for sRGB or 4x channel for sRGB+alpha.

[pajtai]

After trying to pass a buffer from the request npm, I can see that this does not currently work, but from the docs, what kind of buffers can be passed to the constructor?

Buffer containing JPEG, PNG, WebP, GIF* or TIFF image data,

[lovell]

@pajtai This issue relates to the addition of support for uncompressed pixel data input.

The sharp.format attribute will tell you which compressed formats are available to you (depends on sharp+libvips versions).

"I can see that this does not currently work"

If you're still having problems, feel free to create a new issue with more details of the error you're experiencing and, if possible, a code sample.

[pajtai]

Thanks @lovell - I created #247 with code snippet and explanation of what I'm trying to do.

[lovell]

Commit e380576 on the mind branch adds support for raw, uncompressed pixel data input via Buffer or Stream.

[nicolaspanel]

@lovell : could you share an example of how to use raw inputs?

I tried this:

var H = 100, W = 100, C = 1, n = H*W*C, data = new Uint8Array(n);

for (var i=0; i<n; i++) {data[i] = 0;}

sharp(new Buffer(data.buffer), { rawWidth: W, rawHeight: H, rawChannels: C})
        .toBuffer()
        .then(function () {});

but it throws an error ("Input buffer contains unsupported image format")

NB: I'm using v0.13.0 (from master branch)

[lovell]

@nicolaspanel Bonjour, please can you try something like { raw: { width: W, height: H, channels: C} } (as rawWidth etc. are internal attributes).

Test/example: https://github.com/lovell/sharp/blob/master/test/unit/io.js#L915-L928

[nicolaspanel]

It works now 👍
Thanks a lot

[lovell]

v0.13.0 now available, thanks everyone for the original suggestion and help with testing.

[knyga]

I am currently on 0.28.3 and it looks like raw input is not supported. I try to execute basic case mentioned in the case: https://github.com/lovell/sharp/blob/master/test/unit/io.js#L915-L928

[lovell]

@knyga https://sharp.pixelplumbing.com/api-constructor#examples contains an example of using uncompressed pixel data as input.