Creates a 24 bit image from red, green and blue components.
RGBIMAGE(r, g, b, alpha)
r |
- |
An array, the red values. |
g |
- |
An array, the green values. |
b |
- |
An array, the blue values. |
alpha |
- |
Optional, an array, the alpha transparency channel. |
An array, a 24 bit color image.
RGBIMAGE(a, val) sets or resets the interpretation of the data values as composite RGB values.
val = RGBIMAGE(a) returns 1 if the image is a 24 bit RGB image, else 0.
W1: density(spline2(ravel(gnorm(100,1),10), 8));viridis()
W2: (r, g, b) = getrgb(W1);rgbimage(r, g*1.5, b)
W1 contains an image of a random surface shaded with perceptually uniform colors of dark blue, green and yellow.
W2 obtains the individual RGB components and converts the image into a 24 bit color image with the green intensities increased by 50%.
W1: readimage(gethome + "\data\mandrill.bmp")
W2: W1;gray
W3: W2;rgbimage(1)
W1 contains a 24 bit RGB color image. W2 copies the image and re-shades it with a black to white colormap. Although the data values are not changed, the color shading is altered and the data is no longer marked as a 24 bit image. However, because the data values are unchanged, rgbimage(1) restores the original 24 bit color scheme for the image.
Unlike standard images, a 24 bit image does not reference a separate colormap. Instead, each pixel of the image is comprised of a composite 24 bit RED, GREEN, BLUE value packed into a long integer (4 bytes). Use
(r, g, b) = getrgb(image)
to retrieve the separate red, green and blue values from a composite 24 bit image.
image = rgbimage(r, g, b)
to construct a 24 bit composite image from separate RGB values.
Because 24 bit color images do not require a colormap (the colors are implicit), the image can be saved and restored automatically with the correct colors.
isrgb = rgbimage(image)
returns 1 if the image is 24 bit, else 0.
The transparance
See GETRGB to return the red, green and blue components of an image as separate arrays.
See RGBTOCOLOR to convert RGB values into a color index.