The function rgb2ind uses quantization as part of its color reduction algorithm. Reducing the number of colors in an image involves quantization.
#Rgb matlab help how to#
See Dithering for a description of dithering and how to enable or disable it. Note that different methods work better for different images. The quality of the resulting image depends on the approximation method you use, the range of colors in the input image, and whether or not you use dithering. This function provides the following methods for approximating the colors in the original image: Rgb2ind converts an RGB image to an indexed image, reducing the number of colors in the process. The black region in the image shows pixel values that contain no red values, i.e., R = 0.Color (Image Processing Toolbox) Image Processing Toolbox As red becomes mixed with green or blue, gray pixels appear. For example, in the Red Plane image, the white represents the highest concentration of pure red values. The white corresponds to the highest values (purest shades) of each separate color. Notice that each separated color plane in the figure contains an area of white. RGB=reshape(ones(64,1)*reshape(jet(64),1,192),) įigure 2-5: The Separated Color Planes of an RGB Image.It displays each color plane image separately, and also displays the original image.
#Rgb matlab help code#
To further illustrate the concept of the three separate color planes used in an RGB image, the code sample below creates a simple RGB image containing uninterrupted areas of red, green, and blue, and then creates one image for each of its separate color planes (red, green, and blue). To determine the color of the pixel at (2,3), you would look at the RGB triplet stored in (2,3,1:3). For example, the red, green, and blue color components of the pixel (10,5) are stored in RGB(10,5,1), RGB(10,5,2), and RGB(10,5,3), respectively.įigure 2-4 depicts an RGB image of class double.įigure 2-4: The Color Planes of an RGB Image The three color components for each pixel are stored along the third dimension of the data array. A pixel whose color components are (0,0,0) displays as black, and a pixel whose color components are (1,1,1) displays as white. In an RGB array of class double, each color component is a value between 0 and 1. The precision with which a real-life image can be replicated has led to the commonly used term truecolor image.Īn RGB MATLAB array can be of class double, uint8, or uint16. This yields a potential of 16 million colors.
Graphics file formats store RGB images as 24-bit images, where the red, green, and blue components are 8 bits each. The color of each pixel is determined by the combination of the red, green, and blue intensities stored in each color plane at the pixel's location. Introduction (Image Processing Toolbox) Image Processing ToolboxĪn RGB image, sometimes referred to as a truecolor image, is stored in MATLAB as an m-by-n-by-3 data array that defines red, green, and blue color components for each individual pixel.
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