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Merge pull request #1921 from thebostik/decode_jpeg_qtable

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More fixes related to custom jpeg qtables
This commit is contained in:
wiredfool 2016-05-24 09:51:46 +01:00
commit 5839c3b9d1
3 changed files with 35 additions and 6 deletions
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2
PIL/JpegImagePlugin.py
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@ -195,7 +195,7 @@ def DQT(self, marker):
raise SyntaxError("bad quantization table marker")
v = i8(s[0])
if v//16 == 0:
self.quantization[v & 15] = array.array("b", s[1:65])
self.quantization[v & 15] = array.array("B", s[1:65])
s = s[65:]
else:
return # FIXME: add code to read 16-bit tables!

18
Tests/test_file_jpeg.py
View File

@ -303,6 +303,15 @@ class TestFileJpeg(PillowTestCase):
filename = "Tests/images/junk_jpeg_header.jpg"
Image.open(filename)
def _n_qtables_helper(self, n, test_file):
im = Image.open(test_file)
f = self.tempfile('temp.jpg')
im.save(f, qtables=[[n]*64]*n)
im = Image.open(f)
self.assertEqual(len(im.quantization), n)
reloaded = self.roundtrip(im, qtables="keep")
self.assertEqual(im.quantization, reloaded.quantization)
def test_qtables(self):
im = Image.open("Tests/images/hopper.jpg")
qtables = im.quantization
@ -359,6 +368,15 @@ class TestFileJpeg(PillowTestCase):
1: standard_chrominance_qtable
}), 30)
self._n_qtables_helper(1, "Tests/images/hopper_gray.jpg")
self._n_qtables_helper(1, "Tests/images/pil_sample_rgb.jpg")
self._n_qtables_helper(2, "Tests/images/pil_sample_rgb.jpg")
self._n_qtables_helper(3, "Tests/images/pil_sample_rgb.jpg")
self._n_qtables_helper(1, "Tests/images/pil_sample_cmyk.jpg")
self._n_qtables_helper(2, "Tests/images/pil_sample_cmyk.jpg")
self._n_qtables_helper(3, "Tests/images/pil_sample_cmyk.jpg")
self._n_qtables_helper(4, "Tests/images/pil_sample_cmyk.jpg")
# not a sequence
self.assertRaises(Exception, lambda: self.roundtrip(im, qtables='a'))
# sequence wrong length

21
libImaging/JpegEncode.c
View File

@ -148,14 +148,25 @@ ImagingJpegEncode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
if (context->qtables) {
int i;
int quality = 100;
int last_q = 0;
if (context->quality > 0) {
quality = context->quality;
}
for (i = 0; i < context->qtablesLen; i++) {
// TODO: Should add support for none baseline
jpeg_add_quant_table(&context->cinfo, i, &context->qtables[i * DCTSIZE2],
quality, TRUE);
}
for (i = 0; i < context->qtablesLen; i++) {
// TODO: Should add support for none baseline
jpeg_add_quant_table(&context->cinfo, i, &context->qtables[i * DCTSIZE2],
quality, TRUE);
context->cinfo.comp_info[i].quant_tbl_no = i;
last_q = i;
}
if (context->qtablesLen == 1) {
// jpeg_set_defaults created two qtables internally, but we only wanted one.
jpeg_add_quant_table(&context->cinfo, 1, &context->qtables[0],
quality, TRUE);
}
for (i = last_q; i < context->cinfo.num_components; i++) {
context->cinfo.comp_info[i].quant_tbl_no = last_q;
}
} else if (context->quality > 0) {
jpeg_set_quality(&context->cinfo, context->quality, 1);
}