ios - 图像过滤

Question

我有一个应用程序需要在图像过滤器上做一些工作，所以我刚开始研究过滤器，我实现了一些过滤器，比如黑白、Hud、苔藓、亮度、对比度等。

这里有几个我面临的问题要实现的过滤器

1. 怀旧
2. 复古
3. 旧

原始图像

怀旧

复古

旧

如果有人能指导我正确的方向，那就太好了。

提前致谢。

Answer 1

This线程非常有用关于 iphone 中的图像过滤的信息...

编辑

这是我为制作复古图像所做的工作(在我的案例中，复古图像要求略有不同..它的边缘没有阴影)

//first increase contrast a bit...
float contrastValue             =   1.45;
CGImageRef originalImage        =   [myImage CGImage];
CGColorSpaceRef colorSpace      =   CGColorSpaceCreateDeviceRGB();
CGContextRef bitmapContext      =   CGBitmapContextCreate(NULL,CGImageGetWidth(originalImage),CGImageGetHeight(originalImage),8,CGImageGetWidth(originalImage)*4,colorSpace,kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(bitmapContext, CGRectMake(0, 0, CGBitmapContextGetWidth(bitmapContext), CGBitmapContextGetHeight(bitmapContext)), originalImage);
UInt8* data                     =   CGBitmapContextGetData(bitmapContext);
int numComponents               =   4;
int bytesInContext              =   CGBitmapContextGetHeight(bitmapContext) * CGBitmapContextGetBytesPerRow(bitmapContext);
double redIn, greenIn, blueIn;

for (int i = 0; i < bytesInContext; i += numComponents) {
    redIn                       =   (double)data[i]/255.0;
    greenIn                     =   (double)data[i+1]/255.0;
    blueIn                      =   (double)data[i+2]/255.0;
    
    redIn                       -=  0.5;
    redIn                       *=  contrastValue;
    redIn                       +=  0.5;
    redIn                       *=  255.0;
    if (redIn < 0) {
        redIn                   =   0;
    }
    if (redIn > 255) {
        redIn                   =   255;
    }
    
    greenIn                     -=  0.5;
    greenIn                     *=  contrastValue;
    greenIn                     +=  0.5;
    greenIn                     *=  255.0;
    if (greenIn < 0) {
        greenIn                 =   0;
    }
    if (greenIn > 255) {
        greenIn                 =   255;
    }
    
    
    blueIn                      -=  0.5;
    blueIn                      *=  contrastValue;
    blueIn                      +=  0.5;
    blueIn                      *=  255.0;
    if (blueIn < 0) {
        blueIn                  =   0;
    }
    if (blueIn > 255) {
        blueIn                  =   255;
    }
    data[i]                     =   (redIn);
    data[i+1]                   =   (greenIn);
    data[i+2]                   =   (blueIn);
}
CGImageRef outImage             =   CGBitmapContextCreateImage(bitmapContext);
myImage                         =   [UIImage imageWithCGImage:outImage];
CGImageRelease(outImage);

//Then blend it with a yellowish color
UIGraphicsBeginImageContext(myImage.size);
CGContextRef ctx                =   UIGraphicsGetCurrentContext();
CGRect area                     =   CGRectMake(0, 0, myImage.size.width, myImage.size.height);
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -area.size.height);
CGContextSaveGState(ctx);
CGContextClipToMask(ctx, area, myImage.CGImage);
UIColor *color                  =   [UIColor colorWithRed:248.0/255.0 green:254.0/255.0 blue:186.0/255.0 alpha:1.0]; //[UIColor colorWithRed:248.0/255.0 green:254.0/255.0 blue:186.0/255.0 alpha:1.0]
[color set];
CGContextFillRect(ctx, area);
CGContextRestoreGState(ctx);
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
CGContextDrawImage(ctx, area, myImage.CGImage);
myImage                         =   UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

UIGraphicsBeginImageContext(myImage.size);
ctx                             =   UIGraphicsGetCurrentContext();
 area                           =   CGRectMake(0, 0, myImage.size.width, myImage.size.height);
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -area.size.height);
CGContextSaveGState(ctx);
CGContextClipToMask(ctx, area, myImage.CGImage);
color                           =   [UIColor colorWithRed:27.0/255.0 green:50.0/255.0 blue:224.0/255.0 alpha:0.2]; //[UIColor colorWithRed:248.0/255.0 green:254.0/255.0 blue:186.0/255.0 alpha:1.0]
[color set];
CGContextFillRect(ctx, area);
CGContextRestoreGState(ctx);
CGContextSetBlendMode(ctx, kCGBlendModeLighten);
CGContextDrawImage(ctx, area, myImage.CGImage);
processedImage                  =   UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

这可能不适合你..请根据你自己的要求玩这个..从内存中复制，可能有错误..