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Merge pull request #26930 from Kumataro:fix26924
Imgcodecs: gif: support Disposal Method #26930 Close https://github.com/opencv/opencv/issues/26924 ### 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 - [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. - [x] The feature is well documented and sample code can be built with the project CMake
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Kumataro
GitHub
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commit
a63ede6b1d
@ -24,7 +24,6 @@ GifDecoder::GifDecoder() {
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hasRead = false;
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hasTransparentColor = false;
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transparentColor = 0;
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opMode = GRFMT_GIF_Nothing;
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top = 0, left = 0, width = 0, height = 0;
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depth = 8;
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idx = 0;
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@ -66,6 +65,8 @@ bool GifDecoder::readHeader() {
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for (int i = 0; i < 3 * globalColorTableSize; i++) {
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globalColorTable[i] = (uchar)m_strm.getByte();
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}
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CV_CheckGE(bgColor, 0, "bgColor should be >= 0");
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CV_CheckLT(bgColor, globalColorTableSize, "bgColor should be < globalColorTableSize");
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}
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// get the frame count
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@ -81,7 +82,8 @@ bool GifDecoder::readData(Mat &img) {
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return true;
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}
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readExtensions();
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const GifDisposeMethod disposalMethod = readExtensions();
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// Image separator
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CV_Assert(!(m_strm.getByte()^0x2C));
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left = m_strm.getWord();
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@ -93,38 +95,50 @@ bool GifDecoder::readData(Mat &img) {
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imgCodeStream.resize(width * height);
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Mat img_;
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switch (opMode) {
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case GifOpMode::GRFMT_GIF_PreviousImage:
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if (lastImage.empty()){
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img_ = Mat::zeros(m_height, m_width, CV_8UC4);
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} else {
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img_ = lastImage;
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if (lastImage.empty())
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{
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Scalar background(0.0, 0.0, 0.0, 0.0);
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if (bgColor < globalColorTableSize)
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{
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background = Scalar( globalColorTable[bgColor * 3 + 2], // B
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globalColorTable[bgColor * 3 + 1], // G
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globalColorTable[bgColor * 3 + 0], // R
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0); // A
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}
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img_ = Mat(m_height, m_width, CV_8UC4, background);
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} else {
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img_ = lastImage;
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}
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lastImage.release();
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Mat restore;
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switch(disposalMethod)
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{
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case GIF_DISPOSE_NA:
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case GIF_DISPOSE_NONE:
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// Do nothing
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break;
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case GIF_DISPOSE_RESTORE_BACKGROUND:
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if (bgColor < globalColorTableSize)
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{
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const Scalar background = Scalar( globalColorTable[bgColor * 3 + 2], // B
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globalColorTable[bgColor * 3 + 1], // G
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globalColorTable[bgColor * 3 + 0], // R
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0); // A
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restore = Mat(width, height, CV_8UC4, background);
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}
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else
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{
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CV_LOG_WARNING(NULL, cv::format("bgColor(%d) is out of globalColorTableSize(%d)", bgColor, globalColorTableSize));
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}
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break;
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case GifOpMode::GRFMT_GIF_Background:
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// background color is valid iff global color table exists
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CV_Assert(globalColorTableSize > 0);
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if (hasTransparentColor && transparentColor == bgColor) {
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img_ = Mat(m_height, m_width, CV_8UC4,
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Scalar(globalColorTable[bgColor * 3 + 2],
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globalColorTable[bgColor * 3 + 1],
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globalColorTable[bgColor * 3], 0));
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} else {
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img_ = Mat(m_height, m_width, CV_8UC4,
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Scalar(globalColorTable[bgColor * 3 + 2],
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globalColorTable[bgColor * 3 + 1],
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globalColorTable[bgColor * 3], 255));
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}
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break;
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case GifOpMode::GRFMT_GIF_Nothing:
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case GifOpMode::GRFMT_GIF_Cover:
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// default value
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img_ = Mat::zeros(m_height, m_width, CV_8UC4);
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case GIF_DISPOSE_RESTORE_PREVIOUS:
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restore = Mat(img_, cv::Rect(left,top,width,height)).clone();
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break;
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default:
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CV_Assert(false);
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break;
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}
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lastImage.release();
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auto flags = (uchar)m_strm.getByte();
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if (flags & 0x80) {
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@ -189,6 +203,13 @@ bool GifDecoder::readData(Mat &img) {
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// release the memory
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img_.release();
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// update lastImage to dispose current frame.
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if(!restore.empty())
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{
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Mat roi = Mat(lastImage, cv::Rect(left,top,width,height));
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restore.copyTo(roi);
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}
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return hasRead;
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}
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@ -212,8 +233,9 @@ bool GifDecoder::nextPage() {
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}
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}
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void GifDecoder::readExtensions() {
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GifDisposeMethod GifDecoder::readExtensions() {
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uchar len;
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GifDisposeMethod disposalMethod = GifDisposeMethod::GIF_DISPOSE_NA;
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while (!(m_strm.getByte() ^ 0x21)) {
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auto extensionType = (uchar)m_strm.getByte();
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@ -221,13 +243,19 @@ void GifDecoder::readExtensions() {
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// the scope of this extension is the next image or plain text extension
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if (!(extensionType ^ 0xF9)) {
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hasTransparentColor = false;
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opMode = GifOpMode::GRFMT_GIF_Nothing;// default value
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len = (uchar)m_strm.getByte();
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CV_Assert(len == 4);
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auto flags = (uchar)m_strm.getByte();
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const uint8_t packedFields = (uchar)m_strm.getByte();
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const uint8_t dm = (packedFields >> GIF_DISPOSE_METHOD_SHIFT) & GIF_DISPOSE_METHOD_MASK;
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CV_CheckLE(dm, GIF_DISPOSE_MAX, "Unsupported Dispose Method");
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disposalMethod = static_cast<GifDisposeMethod>(dm);
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const uint8_t transColorFlag = packedFields & GIF_TRANS_COLOR_FLAG_MASK;
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CV_CheckLE(transColorFlag, GIF_TRANSPARENT_INDEX_MAX, "Unsupported Transparent Color Flag");
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hasTransparentColor = (transColorFlag == GIF_TRANSPARENT_INDEX_GIVEN);
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m_animation.durations.push_back(m_strm.getWord() * 10); // delay time
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opMode = (GifOpMode)((flags & 0x1C) >> 2);
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hasTransparentColor = flags & 0x01;
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transparentColor = (uchar)m_strm.getByte();
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}
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@ -240,6 +268,8 @@ void GifDecoder::readExtensions() {
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}
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// roll back to the block identifier
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m_strm.setPos(m_strm.getPos() - 1);
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return disposalMethod;
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}
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void GifDecoder::code2pixel(Mat& img, int start, int k){
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@ -247,23 +277,6 @@ void GifDecoder::code2pixel(Mat& img, int start, int k){
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for (int j = 0; j < width; j++) {
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uchar colorIdx = imgCodeStream[idx++];
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if (hasTransparentColor && colorIdx == transparentColor) {
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if (opMode != GifOpMode::GRFMT_GIF_PreviousImage) {
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if (colorIdx < localColorTableSize) {
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img.at<Vec4b>(top + i, left + j) =
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Vec4b(localColorTable[colorIdx * 3 + 2], // B
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localColorTable[colorIdx * 3 + 1], // G
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localColorTable[colorIdx * 3], // R
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0); // A
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} else if (colorIdx < globalColorTableSize) {
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img.at<Vec4b>(top + i, left + j) =
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Vec4b(globalColorTable[colorIdx * 3 + 2], // B
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globalColorTable[colorIdx * 3 + 1], // G
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globalColorTable[colorIdx * 3], // R
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0); // A
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} else {
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img.at<Vec4b>(top + i, left + j) = Vec4b(0, 0, 0, 0);
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}
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}
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continue;
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}
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if (colorIdx < localColorTableSize) {
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@ -437,14 +450,10 @@ bool GifDecoder::getFrameCount_() {
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int len = m_strm.getByte();
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while (len) {
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if (len == 4) {
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int packedFields = m_strm.getByte();
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// 3 bit : Reserved
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// 3 bit : Disposal Method
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// 1 bit : User Input Flag
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// 1 bit : Transparent Color Flag
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if ( (packedFields & 0x01)== 0x01) {
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m_type = CV_8UC4; // Transparent Index is given.
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}
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const uint8_t packedFields = static_cast<uint8_t>(m_strm.getByte()); // Packed Fields
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const uint8_t transColorFlag = packedFields & GIF_TRANS_COLOR_FLAG_MASK;
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CV_CheckLE(transColorFlag, GIF_TRANSPARENT_INDEX_MAX, "Unsupported Transparent Color Flag");
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m_type = (transColorFlag == GIF_TRANSPARENT_INDEX_GIVEN) ? CV_8UC4 : CV_8UC3;
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m_strm.skip(2); // Delay Time
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m_strm.skip(1); // Transparent Color Index
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} else {
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@ -518,7 +527,6 @@ GifEncoder::GifEncoder() {
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m_height = 0, m_width = 0;
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width = 0, height = 0, top = 0, left = 0;
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m_buf_supported = true;
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opMode = GRFMT_GIF_Cover;
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transparentColor = 0; // index of the transparent color, default 0. currently it is a constant number
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transparentRGB = Vec3b(0, 0, 0); // the transparent color, default black
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lzwMaxCodeSize = 12; // the maximum code size, default 12. currently it is a constant number
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@ -665,11 +673,9 @@ bool GifEncoder::writeFrame(const Mat &img) {
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strm.putByte(0x21); // extension introducer
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strm.putByte(0xF9); // graphic control label
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strm.putByte(0x04); // block size, fixed number
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// flag is a packed field, and the first 3 bits are reserved
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uchar flag = opMode << 2;
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if (criticalTransparency)
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flag |= 1;
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strm.putByte(flag);
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const int gcePackedFields = static_cast<int>(GIF_DISPOSE_RESTORE_PREVIOUS << GIF_DISPOSE_METHOD_SHIFT) |
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static_cast<int>(criticalTransparency ? GIF_TRANSPARENT_INDEX_GIVEN : GIF_TRANSPARENT_INDEX_NOT_GIVEN);
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strm.putByte(gcePackedFields);
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strm.putWord(frameDelay);
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strm.putByte(transparentColor);
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strm.putByte(0x00); // end of the extension
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@ -680,7 +686,7 @@ bool GifEncoder::writeFrame(const Mat &img) {
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strm.putWord(top);
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strm.putWord(width);
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strm.putWord(height);
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flag = localColorTableSize > 0 ? 0x80 : 0x00;
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uint8_t flag = localColorTableSize > 0 ? 0x80 : 0x00;
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if (localColorTableSize > 0) {
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std::vector<Mat> img_vec(1, img);
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getColorTable(img_vec, false);
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@ -11,14 +11,35 @@
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namespace cv
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{
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enum GifOpMode
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{
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GRFMT_GIF_Nothing = 0,
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GRFMT_GIF_PreviousImage = 1,
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GRFMT_GIF_Background = 2,
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GRFMT_GIF_Cover = 3
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// See https://www.w3.org/Graphics/GIF/spec-gif89a.txt
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// 23. Graphic Control Extension.
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// <Packed Fields>
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// Reserved : 3 bits
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// Disposal Method : 3 bits
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// User Input Flag : 1 bit
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// Transparent Color Flag : 1 bit
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constexpr int GIF_DISPOSE_METHOD_SHIFT = 2;
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constexpr int GIF_DISPOSE_METHOD_MASK = 7; // 0b111
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constexpr int GIF_TRANS_COLOR_FLAG_MASK = 1; // 0b1
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enum GifDisposeMethod {
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GIF_DISPOSE_NA = 0,
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GIF_DISPOSE_NONE = 1,
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GIF_DISPOSE_RESTORE_BACKGROUND = 2,
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GIF_DISPOSE_RESTORE_PREVIOUS = 3,
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// 4-7 are reserved/undefined.
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GIF_DISPOSE_MAX = GIF_DISPOSE_RESTORE_PREVIOUS,
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};
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enum GifTransparentColorFlag {
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GIF_TRANSPARENT_INDEX_NOT_GIVEN = 0,
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GIF_TRANSPARENT_INDEX_GIVEN = 1,
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GIF_TRANSPARENT_INDEX_MAX = GIF_TRANSPARENT_INDEX_GIVEN,
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};
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//////////////////////////////////////////////////////////////////////
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//// GIF Decoder ////
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//////////////////////////////////////////////////////////////////////
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@ -43,7 +64,6 @@ protected:
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int depth;
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int idx;
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GifOpMode opMode;
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bool hasTransparentColor;
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uchar transparentColor;
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int top, left, width, height;
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@ -66,7 +86,7 @@ protected:
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std::vector<uchar> prefix;
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};
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void readExtensions();
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GifDisposeMethod readExtensions();
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void code2pixel(Mat& img, int start, int k);
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bool lzwDecode();
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bool getFrameCount_();
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@ -366,6 +366,54 @@ TEST(Imgcodecs_Gif, encode_IMREAD_GRAYSCALE) {
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EXPECT_EQ(decoded.channels(), 1);
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}
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// See https://github.com/opencv/opencv/issues/26924
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TEST(Imgcodecs_Gif, decode_disposal_method)
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{
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const string root = cvtest::TS::ptr()->get_data_path();
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const string filename = root + "gifsuite/disposalMethod.gif";
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cv::Animation anim;
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bool ret = false;
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EXPECT_NO_THROW(ret = imreadanimation(filename, anim, cv::IMREAD_UNCHANGED));
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EXPECT_TRUE(ret);
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/* [Detail of this test]
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* disposalMethod.gif has 5 frames to draw 8x8 rectangles with each color index, offsets and disposal method.
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* frame 1 draws {1, ... ,1} rectangle at (1,1) with DisposalMethod = 0.
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* frame 2 draws {2, ... ,2} rectangle at (2,2) with DisposalMethod = 3.
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* frame 3 draws {3, ... ,3} rectangle at (3,3) with DisposalMethod = 1.
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* frame 4 draws {4, ... ,4} rectangle at (4,4) with DisposalMethod = 2.
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* frame 5 draws {5, ... ,5} rectangle at (5,5) with DisposalMethod = 1.
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*
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* To convenience to test, color[N] in the color table has RGB(32*N, some, some).
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* color[0] = RGB(0,0,0) (background color).
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* color[1] = RGB(32,0,0)
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* color[2] = RGB(64,0,255)
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* color[3] = RGB(96,255,0)
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* color[4] = RGB(128,128,128)
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* color[5] = RGB(160,255,255)
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*/
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const int refIds[5][6] =
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{// { 0, 0, 0, 0, 0, 0} 0 is background color.
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{ 0, 1, 1, 1, 1, 1}, // 1 is to be not disposed.
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{ 0, 1, 2, 2, 2, 2}, // 2 is to be restored to previous.
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{ 0, 1, 1, 3, 3, 3}, // 3 is to be left in place.
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{ 0, 1, 1, 3, 4, 4}, // 4 is to be restored to the background color.
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{ 0, 1, 1, 3, 0, 5}, // 5 is to be left in place.
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};
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for(int i = 0 ; i < 5; i++)
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{
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cv::Mat frame = anim.frames[i];
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EXPECT_FALSE(frame.empty());
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EXPECT_EQ(frame.type(), CV_8UC4);
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for(int j = 0; j < 6; j ++ )
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{
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const cv::Scalar p = frame.at<Vec4b>(j,j);
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EXPECT_EQ( p[2], refIds[i][j] * 32 ) << " i = " << i << " j = " << j << " pixels = " << p;
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}
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}
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}
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}//opencv_test
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}//namespace
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