8bit PNG has color type of Bgra8888

[CoenraadS]

Description

I have a 8bit grayscale png. Previously SkiaSharp returned the color type as Index8, but now that format has been removed. I would expect it now to say gray8, and one byte per pixel.

Code

using (var bitmap = SKBitmap.Decode(bytes))

Expected Behavior

gray8, 1 byte per pixel

Actual Behavior

Basic Information

• Version with issue: 1.68.0-preview28
• Last known good version: 1.60.3

Reproduction Link

[mattleibow]

The Index8 pixel format could, and often does, support colors. As a result, an automatic switch is not possible.

However, this is just the default in-memory representation if it can't be detected. If you know you have only gray images, then you can decode to a gray 8 by intercepting the values:

var codec =  SKCodec.Create(data);
var newInfo = new SKImageInfo(codec.Info.Width, codec.Info.Height, SKColorType.Gray8);
var bitmap = SKBitmap.Decode(codec, newInfo);