add IplImage#decode (wrapper of cvDecodeImage)

ext/opencv/cvmat.cpp

@@ -537,31 +537,21 @@ rb_encode_imageM(int argc, VALUE *argv, VALUE self)
   return array;
 }
 
-/*
- * call-seq:
- *   decode_image(buf[, iscolor=CV_LOAD_IMAGE_COLOR]) -> CvMat
- *
- * Reads an image from a buffer in memory.
- *
- * Parameters:
- *   buf <CvMat, Array> - Input array
- *   iscolor <Integer> - Flags specifying the color type of a decoded image (the same flags as CvMat#load)
- */
-VALUE
-rb_decode_imageM(int argc, VALUE *argv, VALUE self)
+CvMat*
+prepare_decoding(int argc, VALUE *argv, int* iscolor, int* need_release)
 {
   VALUE _buff, _iscolor;
   rb_scan_args(argc, argv, "11", &_buff, &_iscolor);
-  int iscolor = NIL_P(_iscolor) ? CV_LOAD_IMAGE_COLOR : NUM2INT(_iscolor);
+  *iscolor = NIL_P(_iscolor) ? CV_LOAD_IMAGE_COLOR : NUM2INT(_iscolor);
 
   CvMat* buff = NULL;
-  int need_release = 0;
+  *need_release = 0;
   switch (TYPE(_buff)) {
   case T_STRING:
     _buff = rb_funcall(_buff, rb_intern("unpack"), 1, rb_str_new("c*", 2));
   case T_ARRAY: {
     int cols = RARRAY_LEN(_buff);
-    need_release = 1;
+    *need_release = 1;
     try {
       buff = rb_cvCreateMat(1, cols, CV_8UC1);
       VALUE *ary_ptr = RARRAY_PTR(_buff);
@@ -583,6 +573,24 @@ rb_decode_imageM(int argc, VALUE *argv, VALUE self)
     raise_typeerror(_buff, "CvMat, Array or String");
   }
 
+  return buff;
+}
+
+/*
+ * call-seq:
+ *   decode_image(buf[, iscolor=CV_LOAD_IMAGE_COLOR]) -> CvMat
+ *
+ * Reads an image from a buffer in memory.
+ *
+ * Parameters:
+ *   buf <CvMat, Array> - Input array
+ *   iscolor <Integer> - Flags specifying the color type of a decoded image (the same flags as CvMat#load)
+ */
+VALUE
+rb_decode_imageM(int argc, VALUE *argv, VALUE self)
+{
+  int iscolor, need_release;
+  CvMat* buff = prepare_decoding(argc, argv, &iscolor, &need_release);
   CvMat* mat_ptr = NULL;
   try {
     mat_ptr = cvDecodeImageM(buff, iscolor);

ext/opencv/cvmat.h

@@ -244,6 +244,8 @@ VALUE new_object(CvSize size, int type);
 VALUE new_mat_kind_object(CvSize size, VALUE ref_obj);
 VALUE new_mat_kind_object(CvSize size, VALUE ref_obj, int cvmat_depth, int channel);
 
+CvMat* prepare_decoding(int argc, VALUE *argv, int* iscolor, int* need_release);
+
 __NAMESPACE_END_CVMAT
 
 inline CvMat*

ext/opencv/iplimage.cpp

@@ -62,6 +62,9 @@ define_ruby_class()
   rb_define_method(rb_klass, "reset_coi", RUBY_METHOD_FUNC(rb_reset_coi), 0); 
 
   rb_define_method(rb_klass, "smoothness", RUBY_METHOD_FUNC(rb_smoothness), -1);
+
+  rb_define_singleton_method(rb_klass, "decode_image", RUBY_METHOD_FUNC(rb_decode_image), -1);
+  rb_define_alias(rb_singleton_class(rb_klass), "decode", "decode_image");
 }
 
 VALUE
@@ -133,6 +136,35 @@ rb_load_image(int argc, VALUE *argv, VALUE self)
   return OPENCV_OBJECT(rb_klass, image);
 }
 
+/*
+ * call-seq:
+ *   decode_image(buf[, iscolor=CV_LOAD_IMAGE_COLOR]) -> CvMat
+ *
+ * Reads an image from a buffer in memory.
+ *
+ * Parameters:
+ *   buf <CvMat, Array, String> - Input array
+ *   iscolor <Integer> - Flags specifying the color type of a decoded image (the same flags as CvMat#load)
+ */
+VALUE
+rb_decode_image(int argc, VALUE *argv, VALUE self)
+{
+  int iscolor, need_release;
+  CvMat* buff = cCvMat::prepare_decoding(argc, argv, &iscolor, &need_release);
+  IplImage* img_ptr = NULL;
+  try {
+    img_ptr = cvDecodeImage(buff, iscolor);
+    if (need_release) {
+      cvReleaseMat(&buff);
+    }
+  }
+  catch (cv::Exception& e) {
+    raise_cverror(e);
+  }
+
+  return OPENCV_OBJECT(rb_klass, img_ptr);
+}
+
 /*
  * Get ROI as CvRect.
  */

ext/opencv/iplimage.h

@@ -26,6 +26,7 @@ VALUE rb_allocate(VALUE klass);
 VALUE rb_initialize(int argc, VALUE *argv, VALUE self);
 
 VALUE rb_load_image(int argc, VALUE *argv, VALUE self);
+VALUE rb_decode_image(int argc, VALUE *argv, VALUE self);
 
 VALUE rb_color_model(VALUE self);
 

test/test_iplimage.rb

@@ -68,6 +68,56 @@ class TestIplImage < OpenCVTestCase
     }
   end
 
+  def test_decode
+    data = nil
+    open(FILENAME_CAT, 'rb') { |f|
+      data = f.read
+    }
+    data_ary = data.unpack("c*")
+    data_mat = CvMat.new(1, data_ary.size).set_data(data_ary)
+    expected = IplImage.load(FILENAME_CAT)
+
+    img1 = IplImage.decode(data)
+    img2 = IplImage.decode(data_ary)
+    img3 = IplImage.decode(data_mat)
+    img4 = IplImage.decode(data, CV_LOAD_IMAGE_COLOR)
+    img5 = IplImage.decode(data_ary, CV_LOAD_IMAGE_COLOR)
+    img6 = IplImage.decode(data_mat, CV_LOAD_IMAGE_COLOR)
+    expected_hash = hash_img(expected)
+
+    [img1, img2, img3, img4, img5, img6].each { |img|
+      assert_equal(IplImage, img.class)
+      assert_equal(expected.rows, img.rows)
+      assert_equal(expected.cols, img.cols)
+      assert_equal(expected.channel, img.channel)
+      assert_equal(expected_hash, hash_img(img))
+    }
+
+    expected_c1 = IplImage.load(FILENAME_CAT, CV_LOAD_IMAGE_GRAYSCALE)
+    img1c1 = IplImage.decode(data, CV_LOAD_IMAGE_GRAYSCALE)
+    img2c1 = IplImage.decode(data_ary, CV_LOAD_IMAGE_GRAYSCALE)
+    img3c1 = IplImage.decode(data_mat, CV_LOAD_IMAGE_GRAYSCALE)
+    expected_hash_c1 = hash_img(expected_c1)
+
+    [img1c1, img2c1, img3c1].each { |img|
+      assert_equal(IplImage, img.class)
+      assert_equal(expected_c1.rows, img.rows)
+      assert_equal(expected_c1.cols, img.cols)
+      assert_equal(expected_c1.channel, img.channel)
+      assert_equal(expected_hash_c1, hash_img(img))
+    }
+
+    assert_raise(TypeError) {
+      IplImage.decode(DUMMY_OBJ)
+    }
+    assert_raise(TypeError) {
+      IplImage.decode(data, DUMMY_OBJ)
+    }
+
+    # Uncomment the following line to show the result images
+    # snap img1, img2, img3
+  end
+
   def test_roi
     img = IplImage.new(20, 30)
     rect = img.roi