How to tell if my pixel data is incorrect or my code is incorrect

[velara3]

I have a library that extracts an image into pixel data. Is there example code that shows how to create a png file?

var png = UPNG.encode([data], width, height, 0);
var buffer = Buffer.from(png);
var file = fs.writeFile("mypng.png", buffer); // images appear blank

Here is the data property:

Exported image:

Another example:

The image is the correct size but also blank.

If I remove the buffer line as shown in the code below I get an error from writeFile:

var png = UPNG.encode([data], width, height, 0);
var file = fs.writeFile("mypng.png", png); 

[TypeError: The "data" argument must be of type string or an instance of Buffer, TypedArray, or DataView. Received an instance of ArrayBuffer

[photopea]

what is "data" in your case? It should be an ArrayBuffer, not a Uint8Array. Could you start with a code in our README, and gradually modify it to what you need?

[velara3]

I changed from this:

var png = UPNG.encode([data], width, height, 0);

to this:

var png = UPNG.encode([data.buffer], width, height, 0);

And now it works. Thank you