ios: change the colors of a UIImage - objective-c

Question

I am working on an Iphone application.
I have png pictures that represents symbols. symbols are all black with a transparent background.
Is there a way I can turn the black color into another one? What I'm looking for is something that can help me choose the color I want and when using the symbols (in a UIImage) I can make them appear the color of my choice.
I have searched around and found a framework called OpenCV that can manipulate images but I cant find out how to recolor the picture.
Any help and suggestion is greatly appreciated.
Thank you

Answer 1

The easiest and shortest:
Way to do that in case when you dealing with UIImageView:
Obj-C:
theImageView.image = [theImageView.image imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
[theImageView setTintColor:[UIColor redColor]];
Swift:
let theImageView = UIImageView(image: UIImage(named:"foo")!.imageWithRenderingMode(UIImageRenderingMode.AlwaysTemplate))
theImageView.tintColor = UIColor.redColor()

Answer 2

hi you want to change remove/ one specific color means use the below category....
.h file:
#import <UIKit/UIKit.h>
#interface UIImage (Color)
+ (UIImage*)setBackgroundImageByColor:(UIColor *)backgroundColor withFrame:(CGRect )rect;
+ (UIImage*) replaceColor:(UIColor*)color inImage:(UIImage*)image withTolerance:(float)tolerance;
+(UIImage *)changeWhiteColorTransparent: (UIImage *)image;
+(UIImage *)changeColorTo:(NSMutableArray*) array Transparent: (UIImage *)image;
//resizing Stuff...
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize;
#end
.m file
#import <QuartzCore/QuartzCore.h>
#import "UIImage+Color.h"
#implementation UIImage (Color)
+ (UIImage* )setBackgroundImageByColor:(UIColor *)backgroundColor withFrame:(CGRect )rect{
// tcv - temporary colored view
UIView *tcv = [[UIView alloc] initWithFrame:rect];
[tcv setBackgroundColor:backgroundColor];
// set up a graphics context of button's size
CGSize gcSize = tcv.frame.size;
UIGraphicsBeginImageContext(gcSize);
// add tcv's layer to context
[tcv.layer renderInContext:UIGraphicsGetCurrentContext()];
// create background image now
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
// [tcv release];
}
+ (UIImage*) replaceColor:(UIColor*)color inImage:(UIImage*)image withTolerance:(float)tolerance {
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
NSUInteger bitmapByteCount = bytesPerRow * height;
unsigned char *rawData = (unsigned char*) calloc(bitmapByteCount, sizeof(unsigned char));
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGColorRef cgColor = [color CGColor];
const CGFloat *components = CGColorGetComponents(cgColor);
float r = components[0];
float g = components[1];
float b = components[2];
//float a = components[3]; // not needed
r = r * 255.0;
g = g * 255.0;
b = b * 255.0;
const float redRange[2] = {
MAX(r - (tolerance / 2.0), 0.0),
MIN(r + (tolerance / 2.0), 255.0)
};
const float greenRange[2] = {
MAX(g - (tolerance / 2.0), 0.0),
MIN(g + (tolerance / 2.0), 255.0)
};
const float blueRange[2] = {
MAX(b - (tolerance / 2.0), 0.0),
MIN(b + (tolerance / 2.0), 255.0)
};
int byteIndex = 0;
while (byteIndex < bitmapByteCount) {
unsigned char red = rawData[byteIndex];
unsigned char green = rawData[byteIndex + 1];
unsigned char blue = rawData[byteIndex + 2];
if (((red >= redRange[0]) && (red <= redRange[1])) &&
((green >= greenRange[0]) && (green <= greenRange[1])) &&
((blue >= blueRange[0]) && (blue <= blueRange[1]))) {
// make the pixel transparent
//
rawData[byteIndex] = 0;
rawData[byteIndex + 1] = 0;
rawData[byteIndex + 2] = 0;
rawData[byteIndex + 3] = 0;
}
byteIndex += 4;
}
UIImage *result = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context)];
CGContextRelease(context);
free(rawData);
return result;
}
+(UIImage *)changeWhiteColorTransparent: (UIImage *)image
{
CGImageRef rawImageRef=image.CGImage;
const float colorMasking[6] = {222, 255, 222, 255, 222, 255};
UIGraphicsBeginImageContext(image.size);
CGImageRef maskedImageRef=CGImageCreateWithMaskingColors(rawImageRef, colorMasking);
{
//if in iphone
CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0.0, image.size.height);
CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0);
}
CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, image.size.width, image.size.height), maskedImageRef);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
CGImageRelease(maskedImageRef);
UIGraphicsEndImageContext();
return result;
}
+(UIImage *)changeColorTo:(NSMutableArray*) array Transparent: (UIImage *)image
{
CGImageRef rawImageRef=image.CGImage;
// const float colorMasking[6] = {222, 255, 222, 255, 222, 255};
const float colorMasking[6] = {[[array objectAtIndex:0] floatValue], [[array objectAtIndex:1] floatValue], [[array objectAtIndex:2] floatValue], [[array objectAtIndex:3] floatValue], [[array objectAtIndex:4] floatValue], [[array objectAtIndex:5] floatValue]};
UIGraphicsBeginImageContext(image.size);
CGImageRef maskedImageRef=CGImageCreateWithMaskingColors(rawImageRef, colorMasking);
{
//if in iphone
CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0.0, image.size.height);
CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0);
}
CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, image.size.width, image.size.height), maskedImageRef);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
CGImageRelease(maskedImageRef);
UIGraphicsEndImageContext();
return result;
}
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
//UIGraphicsBeginImageContext(newSize);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
#end
i changed the removed white color to transparent by this code....
the call will be...
self.rawImage.image=[UIImage changeWhiteColorTransparent:originalStateImage];
i hope this idea will help you....

Answer 3

hi use this category file to change the image entire color....
.h file:
#import <UIKit/UIKit.h>
#interface UIImage (AddtionalFunctionalities)
//TintColor...
- (UIImage *)imageWithTint:(UIColor *)tintColor;
//scale and resize...
-(UIImage*)scaleToSize:(CGSize)size;
#end
.m file:
#import "UIImage+AddtionalFunctionalities.h"
#implementation UIImage (AddtionalFunctionalities)
- (UIImage *)imageWithTint:(UIColor *)tintColor
{
// Begin drawing
CGRect aRect = CGRectMake(0.f, 0.f, self.size.width, self.size.height);
CGImageRef alphaMask;
//
// Compute mask flipping image
//
{
UIGraphicsBeginImageContext(aRect.size);
CGContextRef c = UIGraphicsGetCurrentContext();
// draw image
CGContextTranslateCTM(c, 0, aRect.size.height);
CGContextScaleCTM(c, 1.0, -1.0);
[self drawInRect: aRect];
alphaMask = CGBitmapContextCreateImage(c);
UIGraphicsEndImageContext();
}
//
UIGraphicsBeginImageContext(aRect.size);
// Get the graphic context
CGContextRef c = UIGraphicsGetCurrentContext();
// Draw the image
[self drawInRect:aRect];
// Mask
CGContextClipToMask(c, aRect, alphaMask);
// Set the fill color space
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextSetFillColorSpace(c, colorSpace);
// Set the fill color
CGContextSetFillColorWithColor(c, tintColor.CGColor);
UIRectFillUsingBlendMode(aRect, kCGBlendModeNormal);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Release memory
CGColorSpaceRelease(colorSpace);
CGImageRelease(alphaMask);
return img;
}
-(UIImage*)scaleToSize:(CGSize)size
{
// Create a bitmap graphics context
// This will also set it as the current context
UIGraphicsBeginImageContext(size);
// Draw the scaled image in the current context
[self drawInRect:CGRectMake(0, 0, size.width, size.height)];
// Create a new image from current context
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
// Pop the current context from the stack
UIGraphicsEndImageContext();
// Return our new scaled image
return scaledImage;
}
#end
the method call will be :
self.outputImage.image=[sourceImage imageWithTint:[UIColor redColor]];
if u want to use the image means use this:
self.outputImage.image=[sourceImage imageWithTint:[UIColor colorWithPatternImage:[UIImage imageNamed: #"red.jpg"]]];
i hope this will help you...

Answer 4

Set the Image rendering mode then for color purpose use tintcolor property.
yourImageView.image = [image imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
[yourImageView setTintColor:[UIColor redColor]];

Answer 5

You can create UIView which store UIImageView and change UIview background Color.
UIView *viewForImage = ....;
UIImageView *imageView = .....;
...
[viewForImage addSubview: imageView];
[self.view addSubview:viewForImage];
...
and then use for example
[viewForImage setBackgroundColor: [UIColor redColor]];

Answer 6

For playing with images using objective-c, mainly you have to use Quartz 2D/CoreGraphics framework. I suppose it will be the easiest way for you to accomplish your task.
The link to Quartz 2D guideline is here
, the guideline is pretty comprehensive. Just have a look somewhere in filling the bitmap with color.
Also I've some records about the heavy image processing in my blog, you can have a look, it might be helpfull.
http://levonp.blogspot.de/2012/05/quartz-getting-diff-images-of-two.html
Of course you can do it also using more advanced stuffs like OpenGL, OpenCV, etc.

Answer 7

A very simple solution to change the color of the image. Idea: extensions for UIImage and UIImageView.
Swift 3, Xcode 8.1.
https://stackoverflow.com/a/40884483/4488252
Code sample from my answer (link above):
// use extension UIImage
newImageView = createNewImageView(x: 100)
newImageView.image = UIImage(named: "Apple")?.imageWithColor(newColor: UIColor.blue)
// use extension UIImageView
newImageView = createNewImageView(x: 160)
newImageView.image = UIImage(named: "Apple")
newImageView.imageColor = UIColor.green

Answer 8

For iOS 13.0
Obj-C:
self.yourImageView.image = [self.yourImageView.image imageWithTintColor:[UIColor.redColor]];
Swift:
yourImageView.image = yourImageView.image.withTintColor(UIColor.red);
If the image comes from the Asset Catalog, you can change the rendering in the Attribute Inspector