opencv 数据类型及相互转换

获取Mat的类型：

// myMat即图像数据， type_val为类型标识值
myMat = imread("C:\someimage.jpg");
int type = myMat.type();
或者直接这样
System.out.println(CvType.typeToString(myMat));

类型标示值的含义：

	C1	C2	C3	C4	C(5)	C(6)	C(7)	C(8)
CV_8U	0	8	16	24	32	40	48	56
CV_8S	1	9	17	25	33	41	49	57
CV_16U	2	10	18	26	34	42	50	58
CV_16S	3	11	19	27	35	43	51	59
CV_32S	4	12	20	28	36	44	52	60
CV_32F	5	13	21	29	37	45	53	61
CV_64F	6	14	22	30	38	46	54	62

*：how-to-find-out-what-type-of-a-mat-object-is-with-mattype-in-opencv

颜色通道转换

//将RGB格式的数据转换成BGR格式
cvtColor(RGB_image, BGR_image, COLOR_RGB2BGR);
//将BGR格式的数据转换成灰度图
cvtColor(BGR_imgage, gray_image, COLOR_BGR2GRAY);

类型转换

//将[0,1]范围内的浮点表示的图像转换成8bit整数表示的图像
float_image.convertTo(integer_image, CV_8U, 255.0);

convertTo函数定义如下：
/** @brief Converts an array to another data type with optional scaling.

    The method converts source pixel values to the target data type. saturate_cast\<\> is applied at
    the end to avoid possible overflows:

    \f[m(x,y) = saturate \_ cast<rType>( \alpha (*this)(x,y) +  \beta )\f]
    @param m output matrix; if it does not have a proper size or type before the operation, it is
    reallocated.
    @param rtype desired output matrix type or, rather, the depth since the number of channels are the
    same as the input has; if rtype is negative, the output matrix will have the same type as the input.
    @param alpha optional scale factor.
    @param beta optional delta added to the scaled values.
     */
    void convertTo( OutputArray m, int rtype, double alpha=1, double beta=0 ) const;

*:change-type-of-mat-object-from-cv-32f-to-cv-8u