准确替换图像中的一个像素并通过 Swift 将其放入另一张图像中 [英] Replace exactly one pixel in an image and put it in another image via Swift

问题描述

简单地说，如果我有一个图像 I 和另一个图像 J，我想替换 I(t,s) 位置的 RGB 值) 并将该像素分配给 J(t,s).我如何在 Core Image 或使用自定义内核中做到这一点?

Simply put, if I have an image, I and another image J, I want to replace the RGB value at a position I(t,s) and assign that pixel to J(t,s). How might I do this in Core Image, or using a custom kernel?

考虑到 Core Image 的工作方式，这似乎不是一件容易的事.但是，我想知道是否有一种方法可以提取 (t,s) 处的像素值，创建一个与 J<一样大的图像 K/code> 只用那个像素，然后只在那个点用 K 覆盖 J.只是一个想法，希望有更好的方法.

This seems like it might not be an easy thing to do, considering the way Core Image works. However, I was wondering maybe there was a way to extract the value of the pixel at (t,s), create an image K as large as J with just that pixel, and then overlay J with K only at that one point. Just an idea, hopefully there's a better way.

推荐答案

如果你只想设置一个像素，你可以创建一个小的颜色内核，将传递的目标坐标与当前坐标进行比较并适当地为输出着色.例如:

If you want to set just one pixel, you can create a small color kernel that compares a passed target coordinate with the current coordinate and colors the output appropriately. For example:

let kernel = CIColorKernel(string:
"kernel vec4 setPixelColorAtCoord(__sample pixel, vec2 targetCoord, vec4 targetColor)" +
    "{" +
    "   return int(targetCoord.x) == int(destCoord().x) && int(targetCoord.y) == int(destCoord().y) ? targetColor : pixel; " +
    "}"
)

然后，给定一个图像，假设是纯红色:

Then, given an image, let's say a solid red:

let image = CIImage(color: CIColor(red: 1, green: 0, blue: 0))
    .imageByCroppingToRect(CGRect(x: 0, y: 0, width: 640, height: 640))

如果我们要设置像素为500，100为蓝色:

If we want to set the pixel at 500, 100 to blue:

let targetCoord = CIVector(x: 500, y: 100)
let targetColor = CIColor(red: 0, green: 0, blue: 1)

以下将创建一个名为 final 的 CIImage，在红海中带有一个蓝色像素:

The following will create a CIImage named final with a single blue pixel in a sea of red:

let args = [image, targetCoord, targetColor]
let final = kernel?.applyWithExtent(image.extent, arguments: args)

如果你想绘制多个像素，这可能不是最好的解决方案.

If you want to draw more than one pixel, this may not be the best solution though.

西蒙

这篇关于准确替换图像中的一个像素并通过 Swift 将其放入另一张图像中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！