| Summary: | Chroma subsampling incorrectly described | ||
|---|---|---|---|
| Product: | [Applications] digikam | Reporter: | DrSlony <bugs> |
| Component: | Setup-ImageEditor | Assignee: | Digikam Developers <digikam-bugs-null> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | bugs, caulier.gilles |
| Priority: | NOR | ||
| Version: | 5.0.0 | ||
| Target Milestone: | --- | ||
| Platform: | Other | ||
| OS: | Linux | ||
| Latest Commit: | http://commits.kde.org/digikam/b5be6c56a43af98a639e2668ff99d8a47fd6504a | Version Fixed In: | 5.0.0 |
| Sentry Crash Report: | |||
|
Description
DrSlony
2016-01-31 22:46:21 UTC
Git commit b5be6c56a43af98a639e2668ff99d8a47fd6504a by Maik Qualmann. Committed on 31/01/2016 at 20:01. Pushed by mqualmann into branch 'master'. correct chroma subsampling in JPEGLoader and adds a chroma subsampling mode M +16 -4 libs/dimg/loaders/jpegloader.cpp M +12 -8 libs/dimg/loaders/jpegsettings.cpp http://commits.kde.org/digikam/b5be6c56a43af98a639e2668ff99d8a47fd6504a diff --git a/libs/dimg/loaders/jpegloader.cpp b/libs/dimg/loaders/jpegloader.cpp index c33d785..f33c15c 100644 --- a/libs/dimg/loaders/jpegloader.cpp +++ b/libs/dimg/loaders/jpegloader.cpp @@ -736,9 +736,9 @@ bool JPEGLoader::save(const QString& filePath, DImgLoaderObserver* const observe switch (subsampling) { - case 1: // 2x1, 1x1, 1x1 (4:2:2) : Medium + case 1: // 2x1, 1x1, 1x1 (4:2:2) : Low { - qCDebug(DIGIKAM_DIMG_LOG_JPEG) << "Using LibJPEG medium chroma-subsampling (4:2:2)"; + qCDebug(DIGIKAM_DIMG_LOG_JPEG) << "Using LibJPEG low chroma-subsampling (4:2:2)"; cinfo.comp_info[0].h_samp_factor = 2; cinfo.comp_info[0].v_samp_factor = 1; cinfo.comp_info[1].h_samp_factor = 1; @@ -748,9 +748,9 @@ bool JPEGLoader::save(const QString& filePath, DImgLoaderObserver* const observe break; } - case 2: // 2x2, 1x1, 1x1 (4:1:1) : High + case 2: // 2x2, 1x1, 1x1 (4:2:0) : Medium { - qCDebug(DIGIKAM_DIMG_LOG_JPEG) << "Using LibJPEG high chroma-subsampling (4:1:1)"; + qCDebug(DIGIKAM_DIMG_LOG_JPEG) << "Using LibJPEG medium chroma-subsampling (4:2:0)"; cinfo.comp_info[0].h_samp_factor = 2; cinfo.comp_info[0].v_samp_factor = 2; cinfo.comp_info[1].h_samp_factor = 1; @@ -760,6 +760,18 @@ bool JPEGLoader::save(const QString& filePath, DImgLoaderObserver* const observe break; } + case 3: // 4x1, 1x1, 1x1 (4:1:1) : High + { + qCDebug(DIGIKAM_DIMG_LOG_JPEG) << "Using LibJPEG high chroma-subsampling (4:1:1)"; + cinfo.comp_info[0].h_samp_factor = 4; + cinfo.comp_info[0].v_samp_factor = 1; + cinfo.comp_info[1].h_samp_factor = 1; + cinfo.comp_info[1].v_samp_factor = 1; + cinfo.comp_info[2].h_samp_factor = 1; + cinfo.comp_info[2].v_samp_factor = 1; + break; + } + default: // 1x1 1x1 1x1 (4:4:4) : None { qCDebug(DIGIKAM_DIMG_LOG_JPEG) << "Using LibJPEG none chroma-subsampling (4:4:4)"; diff --git a/libs/dimg/loaders/jpegsettings.cpp b/libs/dimg/loaders/jpegsettings.cpp index b93bfba..afa4beb 100644 --- a/libs/dimg/loaders/jpegsettings.cpp +++ b/libs/dimg/loaders/jpegsettings.cpp @@ -108,18 +108,22 @@ JPEGSettings::JPEGSettings(QWidget* const parent) d->subSamplingCB = new QComboBox(this); d->subSamplingCB->insertItem(0, i18n("None")); // 1x1, 1x1, 1x1 (4:4:4) - d->subSamplingCB->insertItem(1, i18n("Medium")); // 2x1, 1x1, 1x1 (4:2:2) - d->subSamplingCB->insertItem(2, i18n("High")); // 2x2, 1x1, 1x1 (4:1:1) + d->subSamplingCB->insertItem(1, i18n("Low")); // 2x1, 1x1, 1x1 (4:2:2) + d->subSamplingCB->insertItem(2, i18n("Medium")); // 2x2, 1x1, 1x1 (4:2:0) + d->subSamplingCB->insertItem(3, i18n("High")); // 4x1, 1x1, 1x1 (4:1:1) d->subSamplingCB->setWhatsThis(i18n("<p>JPEG Chroma subsampling level \n(color is saved with less resolution " "than luminance):</p>" "<p><b>None</b>=best: uses 4:4:4 ratio. Does not employ chroma " "subsampling at all. This preserves edges and contrasting " - "colors, whilst adding no additional compression</p>" - "<p><b>Medium</b>: uses 4:2:2 ratio. Medium compression: reduces " - "the color resolution by one-third with little to " - "no visual difference</p>" - "<p><b>High</b>: use 4:1:1 ratio. High compression: suits " - "images with soft edges but tends to alter colors</p>" + "colors, whilst adding no additional compression.</p>" + "<p><b>Low</b>: uses 4:2:2 ratio. Low compression: reduces " + "the horizontal color resolution by half with little to " + "no visual difference.</p>" + "<p><b>Medium</b>: uses 4:2:0 ratio. Medium compression: reduces " + "the horizontal and vertical color resolution by half.</p>" + "<p><b>High</b>: use 4:1:1 ratio. High compression: reduces " + "the horizontal color resolution by one quarter. Created " + "images with soft edges but tends to alter colors.</p>" "<p><b>Note: JPEG always uses lossy compression.</b></p>")); d->JPEGGrid->addWidget(d->labelJPEGcompression, 0, 0, 1, 2); Git commit 64db6a9dff56d2b0cf5678c98bfc5e2c88ce8992 by Maik Qualmann. Committed on 01/02/2016 at 19:00. Pushed by mqualmann into branch 'master'. remove rating Low, Medium High from the chroma subsampling settings M +8 -8 libs/dimg/loaders/jpegloader.cpp M +17 -17 libs/dimg/loaders/jpegsettings.cpp http://commits.kde.org/digikam/64db6a9dff56d2b0cf5678c98bfc5e2c88ce8992 +1 for Maik's commit, in my opinion it is now much clearer now to the users. P.S. It would also be nice if we spoke in English and not only in diffs. |