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Revert "Use fast IDCT for JPEG decoding by default (#5072)"

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This reverts commit 2aeedc38c6.
This commit is contained in:
Vijay Vasudevan 2016-11-03 14:54:56 -07:00
parent 501b7137a9
commit b3aa505f6a
3 changed files with 5 additions and 8 deletions
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7
tensorflow/core/lib/jpeg/jpeg_mem.cc
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@ -139,11 +139,8 @@ uint8* UncompressLow(const void* srcdata, FewerArgsForCompiler* argball) {
cinfo.do_fancy_upsampling = boolean(flags.fancy_upscaling);
cinfo.scale_num = 1;
cinfo.scale_denom = ratio;
// Activating this has a quality/speed trade-off implication.
// However, most JPEGs are already compressed, and so the faster IDCT
// should have no effect on training. The fast setting speeds up training on the
// GPU, e.g. by about 30% for smaller networks such as AlexNet.
cinfo.dct_method = JDCT_IFAST;
// Activating this has a quality/speed trade-off implication:
// cinfo.dct_method = JDCT_IFAST;
jpeg_start_decompress(&cinfo);

2
tensorflow/core/lib/jpeg/jpeg_mem_unittest.cc
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@ -165,7 +165,7 @@ TEST(JpegMemTest, Jpeg2) {
// Compare the two images
const int totalerr = ComputeSumAbsoluteDifference(
imgdata1.get(), refdata1.get(), in_w, in_h, stride1, stride1);
CHECK_LE(totalerr, 120000);
CHECK_LE(totalerr, 85000);
}
// check the second image too. Should be bitwise identical to the first.

4
tensorflow/python/ops/image_ops_test.py
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@ -1803,10 +1803,10 @@ class JpegTest(test_util.TensorFlowTestCase):
jpeg0, image0, image1, image2 = sess.run([jpeg0, image0, image1, image2])
# The decoded-encoded image should be similar to the input
self.assertLess(self.averageError(image0, image1), 0.7)
self.assertLess(self.averageError(image0, image1), 0.6)
# We should be very close to a fixpoint
self.assertLess(self.averageError(image1, image2), 0.6)
self.assertLess(self.averageError(image1, image2), 0.02)
# Smooth ramps compress well (input size is 153600)
self.assertGreaterEqual(len(jpeg0), 5000)