c# - What does MSPaint process to eliminate objects in background when PNG image is converted to 4-bit BMP image?

Question

I opened a PNG image, clicked Save As, changed to 16 color Bitmap, and saved it. Then, MSPaint warned about loss of information about transparent and image qualities and, I clicked OK.

As a result, letters behind the black glass object disappeared clearly like this image (Before->After).

By changing PixelFormat or removing transparent area on C# (.Net 4.6.2), I tried to implement this feature just like MSPaint, however, it wasn't removed clearly. In some way, Nothing changed.

Is that not about PixelFormat or ColorDepth? Or, Is there a way to get rid of objects behind another on PNG?

What should I do to implement that?

EDIT 1

Thank you so much, @TaW. By following your method ApplyGamma, I could solve the issue.

question from:https://stackoverflow.com/questions/66057472/what-does-mspaint-process-to-eliminate-objects-in-background-when-png-image-is-c

Answer 1

Waitting for answers