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Update UnpackComponents() to account for 1bpc + DeviceGray (hack for Jbig2)
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This commit is contained in:
BobLd 2025-01-20 06:57:47 +00:00
parent b7e2245eca
commit 5209850af7
1 changed files with 20 additions and 2 deletions
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22
src/UglyToad.PdfPig/Images/ColorSpaceDetailsByteConverter.cs
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@ -34,7 +34,7 @@
if (bitsPerComponent != 8)
{
// Unpack components such that they occupy one byte each
data = UnpackComponents(data, bitsPerComponent);
data = UnpackComponents(data, bitsPerComponent, details.Type);
}
// Remove padding bytes when the stride width differs from the image width
@ -48,7 +48,7 @@
return details.Transform(data);
}
private static Span<byte> UnpackComponents(Span<byte> input, int bitsPerComponent)
private static Span<byte> UnpackComponents(Span<byte> input, int bitsPerComponent, ColorSpace colorSpace)
{
if (bitsPerComponent == 16) // Example with MOZILLA-3136-0.pdf (page 3)
{
@ -72,6 +72,24 @@
int right = (int)Math.Pow(2, bitsPerComponent) - 1;
int u = 0;
// TODO - 1bpc + DeviceGray is required for JBIG2 but needs to be investigated
// Why is this required? This does not belong here imo
if (bitsPerComponent == 1 && colorSpace != ColorSpace.Indexed)
{
foreach (byte b in input)
{
// Enumerate bits in bitsPerComponent-sized chunks from MSB to LSB, masking on the appropriate bits
for (int i = end; i >= 0; --i)
{
unpacked[u++] = (byte)((b >> i) & right) == 1 ? byte.MinValue : byte.MaxValue;
}
}
return unpacked;
}
// Default method
foreach (byte b in input)
{
// Enumerate bits in bitsPerComponent-sized chunks from MSB to LSB, masking on the appropriate bits