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Merge pull request #29894 from pbkx:fix-sunras-encoding-checks

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imgcodecs: fix Sun Raster encoding checks 🤖🤖🤖 - #29894

SunRasterDecoder saves the header's ras_type field in m_encoding but several validation and decoding checks compared RAS_BYTE_ENCODED and RAS_FORMAT_RGB against m_type. This caused valid byte-encoded and RGB-format Sun Raster images to be rejected before their existing decoding paths could be used.

This patch uses the file encoding to make these decisions and limits byte encoding to 8-bit input and RGB-format input to the supported 24- and 32-bit paths. It also selects channel conversion from the file and requested output orders and avoids indexed-palette conversion when decoding truecolor inputs as grayscale.

The regression tests use Sun Raster files written by Netpbm's `pnmtorast -rle` and ImageMagick's SUN encoder. The matching `opencv_extra` PR (opencv/opencv_extra#1408) contains these files and lets them be inspected independently with compatible image viewers. The tests verify exact RLE literal and run values, truncated RLE input, 24- and 32-bit RGB-format input, BGR and RGB output, and grayscale conversion.

The Netpbm file also exposed an existing row-padding error in the RLE path: the decoder consumed a padding byte after even-width rows, although those rows require no padding. The patch now consumes that byte only for odd-width rows.

No public API is changed.

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [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
- [ ] 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:
pbkx
2026-09-10 22:56:54 -07:00
committed by GitHub
parent 5d174966e2
commit 32080eb949
2 changed files with 109 additions and 9 deletions
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23
modules/imgcodecs/src/grfmt_sunras.cpp
View File

@@ -80,7 +80,8 @@ bool SunRasterDecoder::readHeader()
if( m_width > 0 && m_height > 0 &&
(m_bpp == 1 || m_bpp == 8 || m_bpp == 24 || m_bpp == 32) &&
(m_encoding == RAS_OLD || m_encoding == RAS_STANDARD ||
(m_type == RAS_BYTE_ENCODED && m_bpp == 8) || m_type == RAS_FORMAT_RGB) &&
(m_encoding == RAS_BYTE_ENCODED && m_bpp == 8) ||
(m_encoding == RAS_FORMAT_RGB && (m_bpp == 24 || m_bpp == 32))) &&
((m_maptype == RMT_NONE && m_maplength == 0) ||
(m_maptype == RMT_EQUAL_RGB && m_maplength <= palSize && m_maplength > 0 && m_bpp <= 8)))
{
@@ -141,6 +142,9 @@ bool SunRasterDecoder::readHeader()
bool SunRasterDecoder::readData( Mat& img )
{
bool color = img.channels() > 1;
const bool source_is_rgb = m_encoding == RAS_FORMAT_RGB;
const bool output_is_rgb = m_use_rgb;
const bool swap_blue_and_red = source_is_rgb != output_is_rgb;
uchar* data = img.ptr();
size_t step = img.step;
uchar gray_palette[256] = {0};
@@ -159,7 +163,7 @@ bool SunRasterDecoder::readData( Mat& img )
AutoBuffer<uchar> _src(src_pitch + 32);
uchar* src = _src.data();
if( !color )
if( !color && m_bpp <= 8 )
CvtPaletteToGray( m_palette, gray_palette, 1 << m_bpp );
try
@@ -170,7 +174,7 @@ bool SunRasterDecoder::readData( Mat& img )
{
/************************* 1 BPP ************************/
case 1:
if( m_type != RAS_BYTE_ENCODED )
if( m_encoding != RAS_BYTE_ENCODED )
{
for( y = 0; y < m_height; y++, data += step )
{
@@ -239,7 +243,7 @@ bad_decoding_1bpp:
break;
/************************* 8 BPP ************************/
case 8:
if( m_type != RAS_BYTE_ENCODED )
if( m_encoding != RAS_BYTE_ENCODED )
{
for( y = 0; y < m_height; y++, data += step )
{
@@ -304,7 +308,8 @@ bad_decoding_1bpp:
if( data == line_end )
{
if( m_strm.getByte() != 0 )
// Only odd-width 8-bit scanlines contain a padding byte.
if( (m_width & 1) != 0 && m_strm.getByte() != 0 )
goto bad_decoding_end;
line_end += step;
data = line_end - width3;
@@ -325,7 +330,7 @@ bad_decoding_end:
if( color )
{
if( m_type == RAS_FORMAT_RGB || m_use_rgb)
if( swap_blue_and_red )
icvCvt_RGB2BGR_8u_C3R(src, 0, data, 0, Size(m_width,1) );
else
memcpy(data, src, std::min(step, (size_t)src_pitch));
@@ -333,7 +338,7 @@ bad_decoding_end:
else
{
icvCvt_BGR2Gray_8u_C3C1R(src, 0, data, 0, Size(m_width,1),
m_type == RAS_FORMAT_RGB ? 2 : 0 );
source_is_rgb ? 2 : 0 );
}
}
result = true;
@@ -348,10 +353,10 @@ bad_decoding_end:
if( color )
icvCvt_BGRA2BGR_8u_C4C3R( src + 4, 0, data, 0, Size(m_width,1),
(m_type == RAS_FORMAT_RGB || m_use_rgb) ? 2 : 0 );
swap_blue_and_red ? 2 : 0 );
else
icvCvt_BGRA2Gray_8u_C4C1R( src + 4, 0, data, 0, Size(m_width,1),
m_type == RAS_FORMAT_RGB ? 2 : 0 );
source_is_rgb ? 2 : 0 );
}
result = true;
break;

95
modules/imgcodecs/test/test_sunraster.cpp
View File

@@ -10,6 +10,8 @@
#include "test_precomp.hpp"
#include <fstream>
#include <iterator>
#include <vector>
namespace opencv_test { namespace {
@@ -135,4 +137,97 @@ TEST(Imgcodecs_SunRaster, valid_8bpp_grayscale_decodes)
EXPECT_EQ(result.type(), CV_8UC1);
}
TEST(Imgcodecs_SunRaster, byte_encoded_8bpp_decodes)
{
// Generated with Netpbm's pnmtorast -rle.
const String filename = findDataFile("readwrite/sunraster/byte_encoded_8bpp.ras");
uint8_t expected_data[][16] = {
{ 0x11, 0x80, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44,
0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44 },
{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
{ 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff },
{ 0x20, 0x20, 0x40, 0x40, 0x60, 0x60, 0x80, 0x80,
0xa0, 0xa0, 0xc0, 0xc0, 0xe0, 0xe0, 0xff, 0xff },
{ 0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x33,
0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x33 },
{ 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66 },
{ 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99 },
{ 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc,
0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc }
};
const cv::Mat expected(8, 16, CV_8UC1, expected_data);
cv::Mat result;
ASSERT_NO_THROW(result = cv::imread(filename, cv::IMREAD_GRAYSCALE));
ASSERT_FALSE(result.empty());
ASSERT_EQ(expected.size(), result.size());
ASSERT_EQ(expected.type(), result.type());
EXPECT_EQ(0, cv::norm(expected, result, cv::NORM_INF));
}
TEST(Imgcodecs_SunRaster, truncated_byte_encoded_8bpp_returns_empty)
{
const String filename = findDataFile("readwrite/sunraster/byte_encoded_8bpp.ras");
std::ifstream stream(filename.c_str(), std::ios::binary);
ASSERT_TRUE(stream.is_open());
std::vector<uint8_t> buf((std::istreambuf_iterator<char>(stream)),
std::istreambuf_iterator<char>());
const size_t incompleteRleSize = 32 + 3 * 256 + 2;
ASSERT_GT(buf.size(), incompleteRleSize);
buf.resize(incompleteRleSize); // Keep an incomplete RLE escape after the color map.
cv::Mat result;
ASSERT_NO_THROW(result = cv::imdecode(buf, cv::IMREAD_GRAYSCALE));
EXPECT_TRUE(result.empty());
}
typedef tuple<string, int> SunRasterColorParams;
typedef testing::TestWithParam<SunRasterColorParams> Imgcodecs_SunRaster_Color;
TEST_P(Imgcodecs_SunRaster_Color, decodes)
{
const String filename = findDataFile(get<0>(GetParam()));
const int flags = get<1>(GetParam());
uint8_t bgr_data[] = {
30, 20, 10, 60, 50, 40, 0, 0, 255, 0, 255, 0,
255, 0, 0, 0, 255, 255, 255, 0, 255, 255, 255, 0
};
uint8_t rgb_data[] = {
10, 20, 30, 40, 50, 60, 255, 0, 0, 0, 255, 0,
0, 0, 255, 255, 255, 0, 255, 0, 255, 0, 255, 255
};
uint8_t gray_data[] = { 18, 48, 76, 150, 29, 226, 105, 179 };
cv::Mat expected;
if( flags == cv::IMREAD_COLOR )
expected = cv::Mat(2, 4, CV_8UC3, bgr_data);
else if( flags == cv::IMREAD_COLOR_RGB )
expected = cv::Mat(2, 4, CV_8UC3, rgb_data);
else
expected = cv::Mat(2, 4, CV_8UC1, gray_data);
cv::Mat result;
ASSERT_NO_THROW(result = cv::imread(filename, flags));
ASSERT_FALSE(result.empty());
ASSERT_EQ(expected.size(), result.size());
ASSERT_EQ(expected.type(), result.type());
EXPECT_EQ(0, cv::norm(expected, result, cv::NORM_INF));
}
// Generated with ImageMagick's SUN encoder.
INSTANTIATE_TEST_CASE_P(RgbFormat, Imgcodecs_SunRaster_Color,
testing::Combine(
testing::Values(
"readwrite/sunraster/rgb_format_24bpp.ras",
"readwrite/sunraster/rgb_format_32bpp.ras"),
testing::Values(
cv::IMREAD_COLOR,
cv::IMREAD_COLOR_RGB,
cv::IMREAD_GRAYSCALE)));
}} // namespace opencv_test