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Preserve auxiliary channels during CMS transform.

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This commit is contained in:
Jarkko Pöyry 2017-01-28 22:05:49 +02:00
parent fa56b3d255
commit 4a1ad8986f
1 changed files with 101 additions and 0 deletions
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101
_imagingcms.c
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@ -291,6 +291,97 @@ findLCMStype(char* PILmode)
}
}
#define Cms_Min(a, b) ((a) < (b) ? (a) : (b))
static int
pyCMSgetAuxChannelChannel (cmsUInt32Number format, int auxChannelNdx)
{
int numColors = T_CHANNELS(format);
int numExtras = T_EXTRA(format);
if (T_SWAPFIRST(format) && T_DOSWAP(format)) {
// reverse order, before anything but last extra is shifted last
if (auxChannelNdx == numExtras - 1)
return numColors + numExtras - 1;
else
return numExtras - 2 - auxChannelNdx;
}
else if (T_SWAPFIRST(format)) {
// in order, after color channels, but last extra is shifted to first
if (auxChannelNdx == numExtras - 1)
return 0;
else
return numColors + 1 + auxChannelNdx;
}
else if (T_DOSWAP(format)) {
// reverse order, before anything
return numExtras - 1 - auxChannelNdx;
}
else {
// in order, after color channels
return numColors + auxChannelNdx;
}
}
static void
pyCMScopyAux (cmsHTRANSFORM hTransform, Imaging imDst, const Imaging imSrc)
{
cmsUInt32Number dstLCMSFormat;
cmsUInt32Number srcLCMSFormat;
int numSrcExtras;
int numDstExtras;
int numExtras;
int ySize;
int xSize;
int channelSize;
int srcChunkSize;
int dstChunkSize;
int e;
// trivially copied
if (imDst == imSrc)
return;
dstLCMSFormat = cmsGetTransformOutputFormat(hTransform);
srcLCMSFormat = cmsGetTransformInputFormat(hTransform);
// currently, all Pillow formats are chunky formats, but check it anyway
if (T_PLANAR(dstLCMSFormat) || T_PLANAR(srcLCMSFormat))
return;
// copy only if channel format is identical, except OPTIMIZED is ignored as it
// does not affect the aux channel
if (T_FLOAT(dstLCMSFormat) != T_FLOAT(srcLCMSFormat)
|| T_FLAVOR(dstLCMSFormat) != T_FLAVOR(srcLCMSFormat)
|| T_ENDIAN16(dstLCMSFormat) != T_ENDIAN16(srcLCMSFormat)
|| T_BYTES(dstLCMSFormat) != T_BYTES(srcLCMSFormat))
return;
numSrcExtras = T_EXTRA(srcLCMSFormat);
numDstExtras = T_EXTRA(dstLCMSFormat);
numExtras = Cms_Min(numSrcExtras, numDstExtras);
ySize = Cms_Min(imSrc->ysize, imDst->ysize);
xSize = Cms_Min(imSrc->xsize, imDst->xsize);
channelSize = T_BYTES(dstLCMSFormat);
srcChunkSize = (T_CHANNELS(srcLCMSFormat) + T_EXTRA(srcLCMSFormat)) * channelSize;
dstChunkSize = (T_CHANNELS(dstLCMSFormat) + T_EXTRA(dstLCMSFormat)) * channelSize;
for (e = 0; e < numExtras; ++e) {
int y;
int dstChannel = pyCMSgetAuxChannelChannel(dstLCMSFormat, e);
int srcChannel = pyCMSgetAuxChannelChannel(srcLCMSFormat, e);
for (y = 0; y < ySize; y++) {
int x;
char* pDstExtras = imDst->image[y] + dstChannel * channelSize;
const char* pSrcExtras = imSrc->image[y] + srcChannel * channelSize;
for (x = 0; x < xSize; x++)
memcpy(pDstExtras + x * dstChunkSize, pSrcExtras + x * srcChunkSize, channelSize);
}
}
}
static int
pyCMSdoTransform(Imaging im, Imaging imOut, cmsHTRANSFORM hTransform)
{
@ -301,9 +392,19 @@ pyCMSdoTransform(Imaging im, Imaging imOut, cmsHTRANSFORM hTransform)
Py_BEGIN_ALLOW_THREADS
// transform color channels only
for (i = 0; i < im->ysize; i++)
cmsDoTransform(hTransform, im->image[i], imOut->image[i], im->xsize);
// lcms by default does nothing to the auxiliary channels leaving those
// unchanged. To do "the right thing" here, i.e. maintain identical results
// with and without inPlace, we replicate those channels to the output.
//
// As of lcms 2.8, a new cmsFLAGS_COPY_ALPHA flag is introduced which would
// do the same thing automagically. Unfortunately, lcms2.8 is not yet widely
// enough available on all platforms, so we polyfill it here for now.
pyCMScopyAux(hTransform, imOut, im);
Py_END_ALLOW_THREADS
return 0;