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Allow to read PNG image of color_type PNG_COLOR_TYPE_PALETTE with alpha channel

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Correct reading PNG color type palette with or without alpha imread flags -1 or 1
Better not using pnginfo.h, using png_get_tRNS instead
pull/1310/head
Hanusz Leszek 12 years ago
parent abf372d759
commit cf39ba5801
2 changed files with 111 additions and 10 deletions
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  1. 29
      modules/highgui/src/grfmt_png.cpp
  2. 92
      modules/highgui/test/test_grfmt.cpp

29
modules/highgui/src/grfmt_png.cpp
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@ -171,7 +171,9 @@ bool PngDecoder::readHeader()
if( !m_buf.empty() || m_f )
{
png_uint_32 wdth, hght;
int bit_depth, color_type;
int bit_depth, color_type, num_trans=0;
png_bytep trans;
png_color_16p trans_values;
png_read_info( png_ptr, info_ptr );
@ -187,15 +189,22 @@ bool PngDecoder::readHeader()
{
switch(color_type)
{
case PNG_COLOR_TYPE_RGB:
case PNG_COLOR_TYPE_PALETTE:
m_type = CV_8UC3;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
m_type = CV_8UC4;
break;
default:
m_type = CV_8UC1;
case PNG_COLOR_TYPE_RGB:
m_type = CV_8UC3;
break;
case PNG_COLOR_TYPE_PALETTE:
png_get_tRNS( png_ptr, info_ptr, &trans, &num_trans, &trans_values);
//Check if there is a transparency value in the palette
if ( num_trans > 0 )
m_type = CV_8UC4;
else
m_type = CV_8UC3;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
m_type = CV_8UC4;
break;
default:
m_type = CV_8UC1;
}
if( bit_depth == 16 )
m_type = CV_MAKETYPE(CV_16U, CV_MAT_CN(m_type));

92
modules/highgui/test/test_grfmt.cpp
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@ -280,6 +280,98 @@ TEST(Highgui_ImreadVSCvtColor, regression)
EXPECT_LT(actual_avg_diff, MAX_MEAN_DIFF);
EXPECT_LT(actual_maxval, MAX_ABS_DIFF);
}
//Test OpenCV issue 3075 is solved
class CV_GrfmtReadPNGColorPaletteWithAlphaTest : public cvtest::BaseTest
{
public:
void run(int)
{
try
{
// First Test : Read PNG with alpha, imread flag -1
Mat img = imread(string(ts->get_data_path()) + "readwrite/color_palette_alpha.png",-1);
if (img.empty()) ts->set_failed_test_info(cvtest::TS::FAIL_INVALID_TEST_DATA);
ASSERT_TRUE(img.channels() == 4);
uint8_t* img_data = (uint8_t*)img.data;
// Verification first pixel is red in BGRA
ASSERT_TRUE(img_data[0] == 0x00);
ASSERT_TRUE(img_data[1] == 0x00);
ASSERT_TRUE(img_data[2] == 0xFF);
ASSERT_TRUE(img_data[3] == 0xFF);
// Verification second pixel is red in BGRA
ASSERT_TRUE(img_data[4] == 0x00);
ASSERT_TRUE(img_data[5] == 0x00);
ASSERT_TRUE(img_data[6] == 0xFF);
ASSERT_TRUE(img_data[7] == 0xFF);
// Second Test : Read PNG without alpha, imread flag -1
img = imread(string(ts->get_data_path()) + "readwrite/color_palette_no_alpha.png",-1);
if (img.empty()) ts->set_failed_test_info(cvtest::TS::FAIL_INVALID_TEST_DATA);
ASSERT_TRUE(img.channels() == 3);
img_data = (uint8_t*)img.data;
// Verification first pixel is red in BGR
ASSERT_TRUE(img_data[0] == 0x00);
ASSERT_TRUE(img_data[1] == 0x00);
ASSERT_TRUE(img_data[2] == 0xFF);
// Verification second pixel is red in BGR
ASSERT_TRUE(img_data[3] == 0x00);
ASSERT_TRUE(img_data[4] == 0x00);
ASSERT_TRUE(img_data[5] == 0xFF);
// Third Test : Read PNG with alpha, imread flag 1
img = imread(string(ts->get_data_path()) + "readwrite/color_palette_alpha.png",1);
if (img.empty()) ts->set_failed_test_info(cvtest::TS::FAIL_INVALID_TEST_DATA);
ASSERT_TRUE(img.channels() == 3);
img_data = (uint8_t*)img.data;
// Verification first pixel is red in BGR
ASSERT_TRUE(img_data[0] == 0x00);
ASSERT_TRUE(img_data[1] == 0x00);
ASSERT_TRUE(img_data[2] == 0xFF);
// Verification second pixel is red in BGR
ASSERT_TRUE(img_data[3] == 0x00);
ASSERT_TRUE(img_data[4] == 0x00);
ASSERT_TRUE(img_data[5] == 0xFF);
// Fourth Test : Read PNG without alpha, imread flag 1
img = imread(string(ts->get_data_path()) + "readwrite/color_palette_no_alpha.png",1);
if (img.empty()) ts->set_failed_test_info(cvtest::TS::FAIL_INVALID_TEST_DATA);
ASSERT_TRUE(img.channels() == 3);
img_data = (uint8_t*)img.data;
// Verification first pixel is red in BGR
ASSERT_TRUE(img_data[0] == 0x00);
ASSERT_TRUE(img_data[1] == 0x00);
ASSERT_TRUE(img_data[2] == 0xFF);
// Verification second pixel is red in BGR
ASSERT_TRUE(img_data[3] == 0x00);
ASSERT_TRUE(img_data[4] == 0x00);
ASSERT_TRUE(img_data[5] == 0xFF);
}
catch(...)
{
ts->set_failed_test_info(cvtest::TS::FAIL_EXCEPTION);
}
ts->set_failed_test_info(cvtest::TS::OK);
}
};
TEST(Highgui_Image, read_png_color_palette_with_alpha) { CV_GrfmtReadPNGColorPaletteWithAlphaTest test; test.safe_run(); }
#endif
#ifdef HAVE_JPEG

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