1bit PCX conversion fails since 7.3.0

[dittodhole]

Coming from 7.0.0.14, I convert a .png-file to 1bit .pcx-file with the following code:

using System;
using System.Drawing;
using ImageMagick;

using (var bitmap = (Bitmap) Bitmap.FromFile(path))
using (var magickImage = new MagickImage(bitmap))
{
  if (magickImage.HasAlpha)
  {
    magickImage.ColorAlpha(new MagickColor(Color.White)); // in later versions MagickColors.White
  }

  var quantizeSettings = new QuantizeSettings
                         {
                           ColorSpace = ColorSpace.GRAY, // in later versions ColorSpace.Gray
                           Colors = 2
                         };
  magickImage.Quantize(quantizeSettings);

  magickImage.ColorType = ColorType.Bilevel;
  magickImage.Depth = 1;
  magickImage.Format = MagickFormat.Pcx;

  var array = magickImage.ToByteArray();
}

Now, inspecting the PXC header of array at offset 3:

Offset	Size	Description	Value
0	1	Manufacturer	10	:heavy_check_mark:
1	1	PCX version number	5	:heavy_check_mark:
2	1	RLE	1	:heavy_check_mark:
3	1	Depth	1	:heavy_check_mark:
...	...	...	...

With 7.3.0 Depth changes to 8:

offset	size	description	value
0	1	Manufacturer	10	:heavy_check_mark:
1	1	PCX version number	5	:heavy_check_mark:
2	1	RLE	1	:heavy_check_mark:
3	1	Depth	8	:shit: :zap: :bomb:
...	...	...	...

What and why has that behavior changed? How can I get the initial behavior back?

Additionally, the output size has changed (WHY??):

• 7.0.0.14: 1,565 bytes
• 7.0.1: 7,350 bytes :suspect: (this release fixes some alpha-issues I have with some images, so this ain't a problem :grin:)
• 7.3.0: 22,586 bytes :goberserk:
• 7.4.5: 66,341 bytes :trollface:

Best Andreas

[dlemstra]

Thanks for the detailed report, will try to take a look at it later today.

[dlemstra]

Can you share your input image?

[dlemstra]

I can confirm this is a bug and I will need to figure out how to fix this.

And you don't need to do the call to Quantize. This already happens when you change the ColorType to BiLevel.

[dlemstra]

@dittodhole Can you give it another try with the latest release?

[dittodhole]

@dlemstra Thanks for the ping, I will test the new release this eve.

[dittodhole]

@dlemstra Thanks for the fix - I've validated the new version with various .png-files and checked the actual byte content for 7.0.1 vs 7.4.6 :+1: The actual binary output matches between versions 😄