Golang image processing: how to cut and stretch images

Golang image processing: How to cut and stretch images

Introduction:
With the rapid development of the Internet, pictures have become people's daily life and an integral part of the job. In many applications, we often need to perform some special processing on pictures, such as miscutting and stretching. This article will introduce how to use Golang to cross-cut and stretch images, and give corresponding code examples.

1. Cross-cutting of pictures
Cross-cutting refers to the operation of diagonally stretching the image in the horizontal and vertical directions, causing the shape of the image to change. In Golang, we can use the github.com/nfnt/resize package to implement the function of miscutting images.

Code example:

package main

import (
    "github.com/nfnt/resize"
    "image"
    "image/draw"
    "image/jpeg"
    "os"
)

func main() {
    // 读取原始图片
    file, _ := os.Open("input.jpg")
    defer file.Close()
    img, _ := jpeg.Decode(file)

    // 创建一个新的画布，并设置宽度和高度
    width := 800
    height := 600
    dst := image.NewRGBA(image.Rect(0, 0, width, height))

    // 错切参数
    shearX := 0.2 // 水平错切强度
    shearY := 0.4 // 垂直错切强度

    // 进行图片错切操作
    draw.Draw(dst, dst.Bounds(), img, image.ZP, draw.Src)
    for x := 1; x < img.Bounds().Dx(); x++ {
        for y := 1; y < img.Bounds().Dy(); y++ {
            dst.Set(x, y, img.At(x+int(shearX*float64(y)), y+int(shearY*float64(x))))
        }
    }

    // 将处理后的图片保存到文件中
    out, _ := os.Create("output.jpg")
    defer out.Close()
    jpeg.Encode(out, dst, nil)
}

The above code first reads the original image file and declares the width and height of the target image. Then, we create a new canvas and use the draw.Draw function to draw the original image onto the new canvas. Then, in the nested loop, each pixel is staggered according to the staggered parameters, and the result is set to the new canvas. Finally, save the miscropped image to a file.

2. Picture stretching
Stretching refers to changing the size of the picture so that the width or height of the picture becomes larger or smaller. In Golang, we can use the github.com/nfnt/resize package to implement the image stretching function.

Code example:

package main

import (
    "github.com/nfnt/resize"
    "image/jpeg"
    "os"
)

func main() {
    // 读取原始图片
    file, _ := os.Open("input.jpg")
    defer file.Close()
    img, _ := jpeg.Decode(file)

    // 拉伸参数
    width := 800  // 目标宽度
    height := 600 // 目标高度

    // 进行图片拉伸操作
    dst := resize.Resize(uint(width), uint(height), img, resize.NearestNeighbor)

    // 将处理后的图片保存到文件中
    out, _ := os.Create("output.jpg")
    defer out.Close()
    jpeg.Encode(out, dst, nil)
}

The above code first reads the original image file and declares the width and height of the target image. Then, use the resize.Resize function to stretch the original image to the target size. Finally, save the stretched image to a file.

Conclusion:
This article introduces the method of using Golang to cross-cut and stretch images, and gives corresponding code examples. By using the github.com/nfnt/resize package, we can easily perform cross-cutting and stretching operations on images, enriching image processing functions. I hope readers can better understand and use Golang's image processing techniques through the introduction of this article.

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