Create a new image

Use the image, image/color, and image/png packages to create a PNG image.

width := 200
height := 100

upLeft := image.Point{0, 0}
lowRight := image.Point{width, height}

img := image.NewRGBA(image.Rectangle{upLeft, lowRight})

// Colors are defined by Red, Green, Blue, Alpha uint8 values.
cyan := color.RGBA{100, 200, 200, 0xff}

// Set color for each pixel.
for x := 0; x < width; x++ {
    for y := 0; y < height; y++ {
        switch {
        case x < width/2 && y < height/2: // upper left quadrant
            img.Set(x, y, cyan)
        case x >= width/2 && y >= height/2: // lower right quadrant
            img.Set(x, y, color.White)
        default:
            // Use zero value.
        }
    }
}

// Encode as PNG.
f, _ := os.Create("image.png")
png.Encode(f, img)

Output (image.png):

Note: The upper right and lower left quadrants of the image are transparent (the alpha value is 0) and will be the same color as the background.

Go image support

The image package implements a basic 2-D image library without painting or drawing functionality. The article The Go image package has a nice introduction to images, color models, and image formats in Go.

Additionally, the image/draw package provides image composition functions that can be used to perform a number of common image manipulation tasks. The article The Go image/draw package has plenty of examples.

More code examples

Go blueprints: code for com­mon tasks is a collection of handy code examples.

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