Question

I have an application that requires some work on image filters, so I just started working on filters and I achieved few filters like Black & white, Hud, moss,brightness,contrast etc.

Here are few filters that I am facing problem to achieve

1. Nostalgia
2. Vintage
3. Old

Original Image

Nostalgia

vintage

old

If anyone can guide me on the right direction it would be great.

Thanks in advance.

Answer 1

This thread is very informative about image filtering in iphone…

EDIT

This what I have done to make an image vintage (Vintage image requirement in my case was slightly different..It didn’t have shades on the edges)

//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();

This might not work for you as is..Please play with this for your own requirement..Copied from memory, errors possible..