[IMAGING-204] reading monochrome TIFF leads to unhandled exception

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.0-alpha1
• Component/s: Format: TIFF
• Assignee: Unassigned
• Reporter: Thomas Elsner
• Created: 24/Aug/17 18:08
• Updated: 24/Aug/17 18:08

Description

reading monochrome TIFF doesn't work.
wrong function getSamplesAsBytes(bis, samples);
Here with having 1 Bit per Pixel it returns value samples[0] = 255 instead of 1.

Then photometricInterpreter.interpretPixel(imageBuilder, samples, x, y); has a problem
public void interpretPixel(final ImageBuilder imageBuilder, final int[] samples, final int x,
final int y) throws ImageReadException, IOException

{ imageBuilder.setRGB(x, y, indexColorMap[samples[0]]); }

as the indexColorMaps only has two entries (black and white), but not 256 entries

The same problem will occur as the colour does not have 8 Bit.

The fix seems simple:
In routine
void getSamplesAsBytes(final BitInputStream bis, final int[] result) throws IOException {
for (int i = 0; i < bitsPerSample.length; i++) {
final int bits = bitsPerSample[i];
int sample = bis.readBits(bits);
if (bits < 8) {
final int sign = sample & 1;
sample = sample << (8 - bits); // scale to byte.
if (sign > 0)

{ sample = sample | ((1 << (8 - bits)) - 1); // extend to byte }

}...

if 'sign>0' don't fill up to 8 bits, but to 'bits' amount of '1'.
I am not sure about other side effects, so I post this suggestion.