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Merge pull request #23446 from tantei3:bmp_fix

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**Merge with extra**: https://github.com/opencv/opencv_extra/pull/1050

For 32 bits per pixel with 3 or 4 channel destination images, apply scale factor and mask to parse BMP files correctly

closes #23445 

### Pull Request Readiness Checklist
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
This commit is contained in:
tantei3 2023-04-06 17:04:36 +05:30 committed by GitHub
parent 9742c73254
commit 8336a96cb9
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3 changed files with 89 additions and 23 deletions
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77
modules/imgcodecs/src/grfmt_bmp.cpp
View File

@ -127,6 +127,7 @@ bool BmpDecoder::readHeader()
++bit_count;
}
m_rgba_bit_offset[index_rgba] = bit_count;
m_rgba_scale_factor[index_rgba] = 255.0f / mask;
}
}
m_strm.skip( size - 56 );
@ -503,21 +504,33 @@ decode_rle8_bad: ;
break;
/************************* 32 BPP ************************/
case 32:
for( y = 0; y < m_height; y++, data += step )
{
m_strm.getBytes( src, src_pitch );
if( !color )
icvCvt_BGRA2Gray_8u_C4C1R( src, 0, data, 0, Size(m_width,1) );
else if( img.channels() == 3 )
icvCvt_BGRA2BGR_8u_C4C3R(src, 0, data, 0, Size(m_width, 1));
else if ( img.channels() == 4 )
bool has_bit_mask = (m_rgba_bit_offset[0] >= 0) && (m_rgba_bit_offset[1] >= 0) && (m_rgba_bit_offset[2] >= 0);
for( y = 0; y < m_height; y++, data += step )
{
bool has_bit_mask = (m_rgba_bit_offset[0] >= 0) && (m_rgba_bit_offset[1] >= 0) && (m_rgba_bit_offset[2] >= 0);
if ( has_bit_mask )
maskBGRA(data, src, m_width);
else
memcpy(data, src, m_width * 4);
m_strm.getBytes( src, src_pitch );
if( !color )
{
if ( has_bit_mask )
maskBGRAtoGray(data, src, m_width);
else
icvCvt_BGRA2Gray_8u_C4C1R( src, 0, data, 0, Size(m_width,1) );
}
else if( img.channels() == 3 )
{
if ( has_bit_mask )
maskBGRA(data, src, m_width, false);
else
icvCvt_BGRA2BGR_8u_C4C3R(src, 0, data, 0, Size(m_width, 1));
}
else if ( img.channels() == 4 )
{
if ( has_bit_mask )
maskBGRA(data, src, m_width, true);
else
memcpy(data, src, m_width * 4);
}
}
}
result = true;
@ -538,20 +551,40 @@ void BmpDecoder::initMask()
{
memset(m_rgba_mask, 0, sizeof(m_rgba_mask));
memset(m_rgba_bit_offset, -1, sizeof(m_rgba_bit_offset));
for (size_t i = 0; i < 4; i++) {
m_rgba_scale_factor[i] = 1.0f;
}
}
void BmpDecoder::maskBGRA(uchar* des, uchar* src, int num)
void BmpDecoder::maskBGRA(uchar* des, const uchar* src, int num, bool alpha_required)
{
for( int i = 0; i < num; i++, des += 4, src += 4 )
int dest_stride = alpha_required ? 4 : 3;
for( int i = 0; i < num; i++, des += dest_stride, src += 4 )
{
uint data = *((uint*)src);
des[0] = (uchar)((m_rgba_mask[2] & data) >> m_rgba_bit_offset[2]);
des[1] = (uchar)((m_rgba_mask[1] & data) >> m_rgba_bit_offset[1]);
des[2] = (uchar)((m_rgba_mask[0] & data) >> m_rgba_bit_offset[0]);
if (m_rgba_bit_offset[3] >= 0)
des[3] = (uchar)((m_rgba_mask[3] & data) >> m_rgba_bit_offset[3]);
else
des[3] = 255;
des[0] = (uchar)(((m_rgba_mask[2] & data) >> m_rgba_bit_offset[2]) * m_rgba_scale_factor[2]);
des[1] = (uchar)(((m_rgba_mask[1] & data) >> m_rgba_bit_offset[1]) * m_rgba_scale_factor[1]);
des[2] = (uchar)(((m_rgba_mask[0] & data) >> m_rgba_bit_offset[0]) * m_rgba_scale_factor[0]);
if (alpha_required)
{
if (m_rgba_bit_offset[3] >= 0)
des[3] = (uchar)(((m_rgba_mask[3] & data) >> m_rgba_bit_offset[3]) * m_rgba_scale_factor[3]);
else
des[3] = 255;
}
}
}
void BmpDecoder::maskBGRAtoGray(uchar* des, const uchar* src, int num)
{
for( int i = 0; i < num; i++, des++, src += 4 )
{
uint data = *((uint*)src);
int red = (uchar)(((m_rgba_mask[0] & data) >> m_rgba_bit_offset[0]) * m_rgba_scale_factor[0]);
int green = (uchar)(((m_rgba_mask[1] & data) >> m_rgba_bit_offset[1]) * m_rgba_scale_factor[1]);
int blue = (uchar)(((m_rgba_mask[2] & data) >> m_rgba_bit_offset[2]) * m_rgba_scale_factor[2]);
*des = (uchar)(0.299f * red + 0.587f * green + 0.114f * blue);
}
}
//////////////////////////////////////////////////////////////////////////////////////////

4
modules/imgcodecs/src/grfmt_bmp.hpp
View File

@ -74,7 +74,8 @@ public:
protected:
void initMask();
void maskBGRA(uchar* des, uchar* src, int num);
void maskBGRA(uchar* des, const uchar* src, int num, bool alpha_required);
void maskBGRAtoGray(uchar* des, const uchar* src, int num);
enum Origin
{
@ -90,6 +91,7 @@ protected:
BmpCompression m_rle_code;
uint m_rgba_mask[4];
int m_rgba_bit_offset[4];
float m_rgba_scale_factor[4];
};

31
modules/imgcodecs/test/test_grfmt.cpp
View File

@ -331,6 +331,37 @@ TEST(Imgcodecs_Bmp, read_32bit_xrgb)
ASSERT_EQ(data[3], 255);
}
TEST(Imgcodecs_Bmp, rgba_scale)
{
const string root = cvtest::TS::ptr()->get_data_path();
const string filenameInput = root + "readwrite/test_rgba_scale.bmp";
Mat img = cv::imread(filenameInput, IMREAD_UNCHANGED);
ASSERT_FALSE(img.empty());
ASSERT_EQ(CV_8UC4, img.type());
uchar* data = img.ptr();
ASSERT_EQ(data[0], 255);
ASSERT_EQ(data[1], 255);
ASSERT_EQ(data[2], 255);
ASSERT_EQ(data[3], 255);
img = cv::imread(filenameInput, IMREAD_COLOR);
ASSERT_FALSE(img.empty());
ASSERT_EQ(CV_8UC3, img.type());
data = img.ptr();
ASSERT_EQ(data[0], 255);
ASSERT_EQ(data[1], 255);
ASSERT_EQ(data[2], 255);
img = cv::imread(filenameInput, IMREAD_GRAYSCALE);
ASSERT_FALSE(img.empty());
ASSERT_EQ(CV_8UC1, img.type());
data = img.ptr();
ASSERT_EQ(data[0], 255);
}
#ifdef HAVE_IMGCODEC_HDR
TEST(Imgcodecs_Hdr, regression)