Lab TIFFs with alpha cause exceptions (with partial solution)

[bernhardf-ro]

The attached TIFFs use Lab colors and one extra sample for unassociated alpha.
Both cause exceptions in TIFFImageReader.normalizeColor() in line 2251 or 2335 for 8 and 16 bits per channel respectively.
In both cases changing the step of the surrounding for-loop (line 2243 and 2327 respectively) from 3 to 4 fixes the issue.
So I assume the step of the for-loops in that method must include the extras samples of the image being read.
Please see the attachment.

TwelveMonkeys/imageio/imageio-tiff/src/main/java/com/twelvemonkeys/imageio/plugins/tiff/TIFFImageReader.java

Lines 2243 to 2251 in b7d865f

	for (int i = 0; i < data.length; i += 3) {
	// Unsigned scaled form 0...100
	float LStar = (data[i] & 0xff) * 100f / 255.0f;
	float aStar;
	float bStar;
	if (photometricInterpretation == TIFFExtension.PHOTOMETRIC_CIELAB) {
	// -128...127
	aStar = data[i + 1];

TwelveMonkeys/imageio/imageio-tiff/src/main/java/com/twelvemonkeys/imageio/plugins/tiff/TIFFImageReader.java

Lines 2327 to 2335 in b7d865f

	for (int i = 0; i < data.length; i += 3) {
	// Unsigned scaled form 0...100
	float LStar = (data[i] & 0xffff) * 100.0f / scaleL;
	float aStar;
	float bStar;
	if (photometricInterpretation == TIFFExtension.PHOTOMETRIC_CIELAB) {
	// -32768...32767
	aStar = data[i + 1] / 256f;

[haraldk]

Thanks! I'll look into it!

[haraldk]

Thanks for the sampel files and investigation! Should be fixed now in master.

[bernhardf-ro]

Tried master in our integration and can confirm the fix.