Fix final confusion between format and encoding.

Format is file format like jpg, bmp and more,
encoding is color encoding like bgr8, rgb8 and more.

cv_bridge/include/cv_bridge/cv_bridge.h

@@ -277,7 +277,7 @@ struct CvtColorForDisplayOptions {
  * encoding image is passed.
  * - if the output encoding is not empty, it must have sensor_msgs::image_encodings::isColor and
  * isMono return true. It must also be 8 bit in depth
- * - if the input encoding is an OpenCV format (e.g. 8UC1), and if we have 1,3 or 4 channels, it is
+ * - if the input encoding is an OpenCV encoding (e.g. 8UC1), and if we have 1,3 or 4 channels, it is
  * respectively converted to mono, BGR or BGRA.
  * - if the input encoding is 32SC1, this estimate that image as label image and will convert it as
  * bgr image with different colors for each label.

cv_bridge/python/cv_bridge/core.py

@@ -111,7 +111,7 @@ def compressed_imgmsg_to_cv2(self, cmprs_img_msg, desired_encoding = "passthroug
         :rtype: :cpp:type:`cv::Mat`
         :raises CvBridgeError: when conversion is not possible.
 
-        If desired_encoding is ``"passthrough"``, then the returned image has the same format as img_msg.
+        If desired_encoding is ``"passthrough"``, then the returned image has the same encoding as img_msg.
         Otherwise desired_encoding must be one of the standard image encodings
 
         This function returns an OpenCV :cpp:type:`cv::Mat` message on success, or raises :exc:`cv_bridge.CvBridgeError` on failure.
@@ -151,7 +151,7 @@ def imgmsg_to_cv2(self, img_msg, desired_encoding = "passthrough"):
         :rtype: :cpp:type:`cv::Mat`
         :raises CvBridgeError: when conversion is not possible.
 
-        If desired_encoding is ``"passthrough"``, then the returned image has the same format as img_msg.
+        If desired_encoding is ``"passthrough"``, then the returned image has the same encoding as img_msg.
         Otherwise desired_encoding must be one of the standard image encodings
 
         This function returns an OpenCV :cpp:type:`cv::Mat` message on success, or raises :exc:`cv_bridge.CvBridgeError` on failure.

cv_bridge/src/cv_bridge.cpp

@@ -200,17 +200,17 @@ const std::vector<int> getConversionCode(std::string src_encoding, std::string d
 {
   Encoding src_encod = getEncoding(src_encoding);
   Encoding dst_encod = getEncoding(dst_encoding);
-  bool is_src_color_format = enc::isColor(src_encoding) || enc::isMono(src_encoding) ||
+  bool is_src_color_encoding = enc::isColor(src_encoding) || enc::isMono(src_encoding) ||
                              enc::isBayer(src_encoding) || (src_encoding == enc::YUV422);
-  bool is_dst_color_format = enc::isColor(dst_encoding) || enc::isMono(dst_encoding) ||
+  bool is_dst_color_encoding = enc::isColor(dst_encoding) || enc::isMono(dst_encoding) ||
                              enc::isBayer(dst_encoding) || (dst_encoding == enc::YUV422);
   bool is_num_channels_the_same = (enc::numChannels(src_encoding) == enc::numChannels(dst_encoding));
 
-  // If we have no color info in the source, we can only convert to the same format which
+  // If we have no color info in the source, we can only convert to the same encoding which
   // was resolved in the previous condition. Otherwise, fail
-  if (!is_src_color_format) {
-    if (is_dst_color_format)
-      throw Exception("[" + src_encoding + "] is not a color format. but [" + dst_encoding +
+  if (!is_src_color_encoding) {
+    if (is_dst_color_encoding)
+      throw Exception("[" + src_encoding + "] is not a color encoding. but [" + dst_encoding +
                       "] is. The conversion does not make sense");
     if (!is_num_channels_the_same)
       throw Exception("[" + src_encoding + "] and [" + dst_encoding + "] do not have the same number of channel");
@@ -219,9 +219,9 @@ const std::vector<int> getConversionCode(std::string src_encoding, std::string d
 
   // If we are converting from a color type to a non color type, we can only do so if we stick
   // to the number of channels
-  if (!is_dst_color_format) {
+  if (!is_dst_color_encoding) {
     if (!is_num_channels_the_same)
-      throw Exception("[" + src_encoding + "] is a color format but [" + dst_encoding + "] " +
+      throw Exception("[" + src_encoding + "] is a color encoding but [" + dst_encoding + "] " +
                       "is not so they must have the same OpenCV type, CV_8UC3, CV16UC1 ....");
     return std::vector<int>(1, SAME_FORMAT);
   }