MATLAB: How to open jpg image as RGBA

rgba

How to open jpg image as RGBA?

Best Answer

It is never possible to open a jpg image as RGBA. JPEG does not support Alpha bitplanes.

JPEG 2000 supports alpha, but that would be .jp2 file extension not .jpg

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MATLAB: 32Bit RGBA Image

"My Camera give me back an RGBA Image R8|G8|B8|A8 = 32 Bit"

"size is : width*height*(bpp/3)"

Shouldn't that be width*height*(bpp/4) ?

Assuming it's 4 bytes per pixel, and that imgRaw is indeed of class uint8:

img = permute(reshape(imgRaw, 4, width, height), [3, 2, 1])
imgRGB = img(:, :, 1:3);  %discard alpha channel which is all 0
imshow(imgRGB);

This assumes that the image pixel are stored in row-major order, which your code also assumed.

MATLAB: Converting CMYK JPG to RGB JPG

Hi Jacob, the first input to the 'applycform' function needs to be a matrix of the image data, rather than the path to the file itself. You are passing in a character vector for that argument, so the function assumes that you are using a named color profile, and errors out accordingly since the encoding 'C' from 'makecform' does not match.

Since 'imread' does not support CMYK JPG files in the first place, this puts us in a tricky situation. What you really need to do, is perform the conversion before being able to work with it at all in MATLAB. There are third-party tools that would allow you to do this conversion.

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Related Solutions

MATLAB: 32Bit RGBA Image

MATLAB: Converting CMYK JPG to RGB JPG

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