color images are always saved as JPG by default (#1272)

* use jpg for color images always * add colorOutput variable * fix typos * remove dither * add box * clarify png * remove debug code * remove unneeded check
2026-04-14 21:18:45 +00:00 · 2026-03-17 13:41:41 -07:00
parent 249f823f01
commit f5fe8d93b0
6 changed files with 35 additions and 10 deletions
--- a/README.md
+++ b/README.md
@@ -272,7 +272,8 @@ PROCESSING:
  --whiteborders        Disable autodetection and force white borders
  --coverfill           Center-crop only the cover to fill target device screen
  --forcecolor          Don't convert images to grayscale
-  --forcepng            Create PNG files instead JPEG
+  --forcepng            Create PNG files instead JPEG for black and white images
+  --force-png-rgb       Force color images to be saved as PNG
  --pnglegacy           Use a more compatible 8 bit PNG instead of 4 bit.
  --noquantize          Don't quantize PNG images to 16 colors
  --mozjpeg             Create JPEG files using mozJpeg
--- a/gui/KCC.ui
+++ b/gui/KCC.ui
@@ -801,7 +801,7 @@ Useful for really weird PDFs.</string>
       <item row="4" column="0">
        <widget class="QCheckBox" name="mozJpegBox">
         <property name="toolTip">
-          <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; text-decoration: underline;&quot;&gt;Unchecked - JPEG&lt;br/&gt;&lt;/span&gt;Use JPEG files&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; text-decoration: underline;&quot;&gt;Indeterminate - force PNG&lt;br/&gt;&lt;/span&gt;Create PNG files instead JPEG&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; text-decoration: underline;&quot;&gt;Checked - mozJpeg&lt;br/&gt;&lt;/span&gt;10-20% smaller JPEG file, with the same image quality, but processing time multiplied by 2&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+          <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; text-decoration: underline;&quot;&gt;Unchecked - JPEG&lt;br/&gt;&lt;/span&gt;Use JPEG files&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; text-decoration: underline;&quot;&gt;Indeterminate - force PNG&lt;br/&gt;&lt;/span&gt;Create PNG files instead JPEG for black and white images&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; text-decoration: underline;&quot;&gt;Checked - mozJpeg&lt;br/&gt;&lt;/span&gt;10-20% smaller JPEG file, with the same image quality, but processing time multiplied by 2&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
         </property>
         <property name="text">
          <string>JPEG/PNG/mozJpeg</string>
@@ -965,6 +965,16 @@ May crop top/bottom or left/right depending on source aspect ratio. Not implemen
         </property>
        </widget>
       </item>
+       <item row="11" column="2">
+        <widget class="QCheckBox" name="forcePngRgbBox">
+         <property name="toolTip">
+          <string>Force full color images to be saved in lossless PNG format, dramatically increases the filesize.</string>
+         </property>
+         <property name="text">
+          <string>Force PNG RGB</string>
+         </property>
+        </widget>
+       </item>
      </layout>
     </widget>
    </item>
--- a/kindlecomicconverter/KCC_gui.py
+++ b/kindlecomicconverter/KCC_gui.py
@@ -351,6 +351,8 @@ class WorkerThread(QThread):
            options.rotateright = True
        if GUI.rotateFirstBox.isChecked():
            options.rotatefirst = True
+        if GUI.forcePngRgbBox.isChecked():
+            options.force_png_rgb = True
        if GUI.mozJpegBox.checkState() == Qt.CheckState.PartiallyChecked:
            options.forcepng = True
        elif GUI.mozJpegBox.checkState() == Qt.CheckState.Checked:
@@ -1054,6 +1056,7 @@ class KCCGUI(KCC_ui.Ui_mainWindow):
                                           'coverFillBox': GUI.coverFillBox.checkState(),
                                           'metadataTitleBox': GUI.metadataTitleBox.checkState(),
                                           'mozJpegBox': GUI.mozJpegBox.checkState(),
+                                           'forcePngRgbBox': GUI.forcePngRgbBox.checkState(),
                                           'pngLegacyBox': GUI.pngLegacyBox.checkState(),
                                           'noQuantizeBox': GUI.noQuantizeBox.checkState(),
                                           'jpegQualityBox': GUI.jpegQualityBox.checkState(),
--- a/kindlecomicconverter/KCC_ui.py
+++ b/kindlecomicconverter/KCC_ui.py
@@ -492,6 +492,11 @@ class Ui_mainWindow(object):

        self.gridLayout_2.addWidget(self.pngLegacyBox, 11, 0, 1, 1)

+        self.forcePngRgbBox = QCheckBox(self.optionWidget)
+        self.forcePngRgbBox.setObjectName(u"forcePngRgbBox")
+
+        self.gridLayout_2.addWidget(self.forcePngRgbBox, 11, 2, 1, 1)
+

        self.gridLayout.addWidget(self.optionWidget, 5, 0, 1, 2)

@@ -745,7 +750,7 @@ class Ui_mainWindow(object):
 #endif // QT_CONFIG(tooltip)
        self.qualityBox.setText(QCoreApplication.translate("mainWindow", u"Panel View 4/2/HQ", None))
 #if QT_CONFIG(tooltip)
-        self.mozJpegBox.setToolTip(QCoreApplication.translate("mainWindow", u"<html><head/><body><p><span style=\" font-weight:600; text-decoration: underline;\">Unchecked - JPEG<br/></span>Use JPEG files</p><p><span style=\" font-weight:600; text-decoration: underline;\">Indeterminate - force PNG<br/></span>Create PNG files instead JPEG</p><p><span style=\" font-weight:600; text-decoration: underline;\">Checked - mozJpeg<br/></span>10-20% smaller JPEG file, with the same image quality, but processing time multiplied by 2</p></body></html>", None))
+        self.mozJpegBox.setToolTip(QCoreApplication.translate("mainWindow", u"<html><head/><body><p><span style=\" font-weight:600; text-decoration: underline;\">Unchecked - JPEG<br/></span>Use JPEG files</p><p><span style=\" font-weight:600; text-decoration: underline;\">Indeterminate - force PNG<br/></span>Create PNG files instead JPEG for black and white images</p><p><span style=\" font-weight:600; text-decoration: underline;\">Checked - mozJpeg<br/></span>10-20% smaller JPEG file, with the same image quality, but processing time multiplied by 2</p></body></html>", None))
 #endif // QT_CONFIG(tooltip)
        self.mozJpegBox.setText(QCoreApplication.translate("mainWindow", u"JPEG/PNG/mozJpeg", None))
 #if QT_CONFIG(tooltip)
@@ -797,6 +802,10 @@ class Ui_mainWindow(object):
        self.pngLegacyBox.setToolTip(QCoreApplication.translate("mainWindow", u"Use a more compatible 8 bit PNG instead of 4 bit.", None))
 #endif // QT_CONFIG(tooltip)
        self.pngLegacyBox.setText(QCoreApplication.translate("mainWindow", u"PNG Legacy Mode", None))
+#if QT_CONFIG(tooltip)
+        self.forcePngRgbBox.setToolTip(QCoreApplication.translate("mainWindow", u"Force full color images to be saved in lossless PNG format, dramatically increases the filesize.", None))
+#endif // QT_CONFIG(tooltip)
+        self.forcePngRgbBox.setText(QCoreApplication.translate("mainWindow", u"Force PNG RGB", None))
        self.gammaLabel.setText(QCoreApplication.translate("mainWindow", u"Gamma: Auto", None))
        self.jpegQualityLabel.setText(QCoreApplication.translate("mainWindow", u"JPEG Quality:", None))
    # retranslateUi
--- a/kindlecomicconverter/comic2ebook.py
+++ b/kindlecomicconverter/comic2ebook.py
@@ -689,7 +689,6 @@ def imgFileProcessing(work):
        workImg = image.ComicPageParser((dirpath, afile), opt)
        for i in workImg.payload:
            img = image.ComicPage(opt, *i)
-            is_color = (opt.forcecolor and img.color)
            if opt.cropping == 2 and not opt.webtoon:
                img.cropPageNumber(opt.croppingp, opt.croppingm)
            if opt.cropping == 1 and not opt.webtoon:
@@ -701,9 +700,9 @@ def imgFileProcessing(work):

            img.autocontrastImage()
            img.resizeImage()
-            img.optimizeForDisplay(opt.eraserainbow, is_color)
+            img.optimizeForDisplay(opt.eraserainbow, img.colorOutput)

-            if is_color:
+            if img.colorOutput:
                pass
            elif opt.forcepng:
                img.convertToGrayscale()
@@ -1412,7 +1411,9 @@ def makeParser():
    output_options.add_argument("--eraserainbow", action="store_true", dest="eraserainbow", default=False,
                                help="Erase rainbow effect on color eink screen by attenuating interfering frequencies")
    processing_options.add_argument("--forcepng", action="store_true", dest="forcepng", default=False,
-                                    help="Create PNG files instead JPEG")
+                                    help="Create PNG files instead JPEG for black and white images")
+    processing_options.add_argument("--force-png-rgb", action="store_true", dest="force_png_rgb", default=False,
+                                    help="Force color images to be saved as PNG")
    processing_options.add_argument("--pnglegacy", action="store_true", dest="pnglegacy", default=False,
                                    help="Use a more compatible 8 bit png instead of 4 bit")
    processing_options.add_argument("--noquantize", action="store_true", dest="noquantize", default=False,
--- a/kindlecomicconverter/image.py
+++ b/kindlecomicconverter/image.py
@@ -277,6 +277,8 @@ class ComicPage:
        self.original_color_mode = image.mode
        # TODO: color check earlier
        self.image = image.convert("RGB")
+        self.color = self.colorCheck()
+        self.colorOutput = self.color and self.opt.forcecolor
        self.fill = fill
        self.rotated = False
        self.orgPath = os.path.join(path[0], path[1])
@@ -295,8 +297,7 @@ class ComicPage:
        if not hasattr(Image, 'Resampling'):
            Image.Resampling = Image

-    @cached_property
-    def color(self):
+    def colorCheck(self):
        if self.original_color_mode in ("L", "1"):
            return False
        if self.opt.webtoon:
@@ -405,7 +406,7 @@ class ComicPage:
            raise RuntimeError('Cannot save image. ' + str(err))

    def save_with_codec(self, image, targetPath):
-        if self.opt.forcepng:
+        if self.opt.forcepng and (not self.colorOutput or self.opt.force_png_rgb):
            image.info.pop('transparency', None)
            if self.opt.iskindle and ('MOBI' in self.opt.format or 'EPUB' in self.opt.format):
                targetPath += '.gif'