2014/10/15 下午 10:04:37

iphone Programming Glossary: blend

Retrieving a pixel alpha value for a UIImage

http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage

I did not in fact need to translate between UIKit coordinates and Core Graphics coordinates. However after setting the blend mode my alpha values were what I expected CGContextSetBlendMode context kCGBlendModeCopy iphone uikit core graphics quartz.. y axis pointing up while in UIKit it points down. See the docs . Edit after reading code You also want to set the blend mode to replace before drawing the image since you want the image's alpha value not the one which was in the context's buffer..

How would I tint an image programatically on the iPhone?

http://stackoverflow.com/questions/1117211/how-would-i-tint-an-image-programatically-on-the-iphone

on the iPhone I would like to tint an image with a color reference. The results should look like the Multiply blending mode in Photoshop where whites would be replaced with tint I will be changing the color value continuously. Follow up.. make color too saturated CGContextFillRect context rect draw base UIImage imageNamed @ someImage.png drawInRect rect blendMode kCGBlendModeOverlay alpha 1.0 draw image iphone cocoa touch image processing share improve this question First.. and override the drawRect method. Your class needs a UIColor property let's call it overlayColor to hold the blend color and a custom setter that forces a redraw when the color changes. Something like this void setOverlayColor UIColor..

How can I change the saturation of an UIImage?

http://stackoverflow.com/questions/1144768/how-can-i-change-the-saturation-of-an-uiimage

context 0.0 0.0 0.0 desaturation CGContextFillRect context rect CGContextRestoreGState context restore state to reset blend mode @end Now in your view controller's viewDidLoad method put the view on screen and set it's saturation like this void..

How to merge the perspective image(3D Transform)?

http://stackoverflow.com/questions/12457047/how-to-merge-the-perspective-image3d-transform

that contain the distorted image to put on top with the background of that image being 0 alpha that way you could blend the images using your above code. So what you are truly looking for is how to apply a 3D transform to an image. More precisely.. this is not available on iOS as of iOS 5.1. So you are left with a few choices If you want to display only the result blend and not manipulate it you can use two UIImageView s on top of each other the one containing the perspective image being.. containing the perspective image being transformed using a cleverly designed CATransform3D If you absolutely need to blend the images you will need to use another framework such as OpenCV warpPerspective is the function you are looking for or..

blend two uiimages

http://stackoverflow.com/questions/1309757/blend-two-uiimages

two uiimages I'm trying to blend a background with a foreground image where the foreground image is a transparent image.. two uiimages I'm trying to blend a background with a foreground image where the foreground image is a transparent image with lines on it. I am trying to.. bounds UIImage imageNamed @ bkgnd.jpg .CGImage CGContextSetBlendMode context kCGBlendModeSourceIn This is my image to blend in CGContextDrawImage context bounds UIImage imageNamed @ over.png .CGImage UIImage outputImage UIGraphicsGetImageFromCurrentImageContext..

iPhone development: pointer being freed was not allocated

http://stackoverflow.com/questions/1424210/iphone-development-pointer-being-freed-was-not-allocated

points up CGContextTranslateCTM context 0 sp.image.size.height CGContextScaleCTM context 1.0 1.0 Get the result of the blending of the masked overlay and the base image CGContextDrawImage context rect overlayMasked.CGImage Set the blend mode for.. of the blending of the masked overlay and the base image CGContextDrawImage context rect overlayMasked.CGImage Set the blend mode for the next drawn image CGContextSetBlendMode context kCGBlendModeOverlay Component image drawn CGContextDrawImage.. context kCGBlendModeOverlay Component image drawn CGContextDrawImage context rect sp.image.CGImage UIImage blendedImage UIGraphicsGetImageFromCurrentImageContext UIGraphicsEndImageContext CGImageRelease MaskedImage return blendedImage..

composite colors: CALayer and blend mode on iPhone

http://stackoverflow.com/questions/1658751/composite-colors-calayer-and-blend-mode-on-iphone

colors CALayer and blend mode on iPhone I'm trying to use core image on the iphone. I'm able to composite my colors using quartz to draw an uiview.. more resources . So I have a white mask I want to use to filter a background bitmap and I want to try different blending mode. Unfortunately the layers are only adding their colors. Here is my code @implementation WhiteLayerHelper void drawLayer.. WhiteLayerHelper void drawLayer CALayer theLayer inContext CGContextRef myContext draw a white overlay with special blending and alpha values so that the saturation can be animated CGContextSetBlendMode myContext kCGBlendModeSaturation CGContextSetRGBFillColor..

How to tint a transparent PNG image in iPhone?

http://stackoverflow.com/questions/3514066/how-to-tint-a-transparent-png-image-in-iphone

in iPhone I know it's possible to tint a rectangular image by drawing a CGContextFillRect over it and setting the blend mode. However I can't figure out how to do a tint on a transparent image such as an icon. It must be possible since the.. the contrary if you have either a non greyscale image OR you have highlights and shadows that should be preserved the blend mode kCGBlendModeColor is the way to go. White will stay white and black will stay black as the lightness of the image is.. the lightness of the image is preserved. This mode is just made for tinting it is the same as Photoshop's Color layer blend mode disclaimer slightly differing results may happen . Note that tinting alpha pixels does not work correctly neither in..

Overlay Color Blend in OpenGL ES / iOS / Cocos2d

http://stackoverflow.com/questions/8771413/overlay-color-blend-in-opengl-es-ios-cocos2d

solution. I started with this image And the basic idea was to draw a rectangle over it in a certain color and apply a blending mode to the image only where the alpha is 1.0 Here is the Code this is part of a Cocos2d project although I think it.. My Questions are How can I remove or fix this error How can keep only the alpha of the image shield and apply the blend overlay color Update This is an example of what I would like with the correct blends iphone ios opengl es cocos2d iphone.. of the image shield and apply the blend overlay color Update This is an example of what I would like with the correct blends iphone ios opengl es cocos2d iphone share improve this question apply a blending mode to the image only where the..