SamplesPerPixel broken when header.ColorType = ColorType.PaletteUsed | ColorType.ColorUsed

[earok]

SamplesPerPixel seems to return 0 on at least some 256 color images, resulting in some of the lines having incorrect filter applied.

Suggested fix might be adding a case for "case ColorType.PaletteUsed | ColorType.ColorUsed":

		switch (header.ColorType)
		{
			case ColorType.None:
				return 1;

			case ColorType.PaletteUsed | ColorType.ColorUsed:
			case ColorType.PaletteUsed:
				return 1;

			case ColorType.ColorUsed:
				return 3;
			case ColorType.AlphaChannelUsed:
				return 2;
			case ColorType.ColorUsed | ColorType.AlphaChannelUsed:
				return 4;
			default:
				return 0;
		}

[ThomasHoevel]

logo.zip

The attached image uses the flags ColorType.PaletteUsed | ColorType.ColorUsed, but still cannot be opened with the fix given above.
It seems that "data" would have to have twice as many bytes as there actually are.

Any help to get BigGustave read this image file will be appreciated.
I don't know where that image originally came from.