Some PNGs result in a black alpha channel, most don't.

I have a REST call on my server that takes in a buffer of an image sent from the client along with information for cropping.

The code works 99% of the time but every so often I encounter a PNG image that does not preserve the alpha channel and it ends up black.

This is the (simplified) code:

(github does not want to format this code nicely for some reason… so here is a screenshot as well)

if (fileType === 'jpeg' || fileType === 'jpg') { console.log('Is jpg making backgroung alpha 1'); s = s.background({r: 255, g: 255, b: 255, alpha: 1}); } else { s = s.background({r: 255, g: 255, b: 255, alpha: 0}); s = s.png({progressive: true, force: true}); } s = s.extend(padding); if (fileType === 'jpeg' || fileType === 'jpg') { s = s.flatten(); } s .toBuffer((err, buffer) => { s = sharp(buffer); } }

I do some cropping and calculating variable padding prior to that.

PNG it works with:

PNG it does not work with:

This is the result of the second one after running it through the code.

I cannot figure out what is going on, maybe some more knowledgeable help on the subject or the PNG fits an edge case?

Note: the call to .png() was added today to see if forcing it to png would help, it didn’t, and has been working for most PNGs without it up till now.

[yharaskrik]

@mjgallag I just updated to 0.21.0 and unfortunately it seems that the “swinging with the starts” image still comes out black. Even after moving the deprecated background call to the .extends call I had below.

[lovell]

Closing due to inactivity but please feel free to re-open with more details, including a standalone code sample, if the problem persists.