Scale Mat Image

The image was taken by a russian photographer in the early 1900s using one of the early color cameras.

Scale mat image.

Cv2 resize along width or horizontal axis cv2 resize image vertically. Note that the matrix has data type double with values outside of the range 0 1 including negative values. In the following example scale percent value holds the percentage by which image has to be scaled. In the dsize we will keep the width same as that of original image but change the height.

Setting and getting pixel values of a gray image in c. The image on the right. Intensity val 0 contains a value from 0 to 255. Dst a mat object representing the destination output image for this operation.

Note the ordering of x and y. Resizing or rescaling a mat is somewhat easier than dealing with a iplimage. You will need to create another image with the new size or scale and apply a resize operation. The code below illustrates these operations on both data types.

The image on the left is part of a historic collection of photographs called the prokudin gorskii collection. Providing a value 100 downscales the image provided. If a has more than two dimensions imresize only resizes the first two dimensions. Fx a variable of the type double representing the scale factor along the horizontal axis.

Since in opencv images are represented by the same structure as matrices we use the same convention for both cases the 0 based row index or y. Because the data range of the matrix is outside the default display range of imshow every pixel with a positive value displays as white and every pixel with a negative or zero value displays as black it is challenging to see the edges of the. Here is an example for a single channel grey scale image type 8uc1 and pixel coordinates x and y. In the following example we will scale the image only along y axis or vertical axis.

Width of the output image remains unchanged from that of the source image. Display the result of the operation. B imresize a scale returns image b that is scale times the size of a the input image a can be a grayscale rgb or binary image. The color channels of the image are misaligned because of the mechanical nature of the camera.

We will use this scale percent value along with original image s dimensions to calculate the width and height of output image. If scale is in the range 0 1 b is smaller than a.