iOS/Objective C:将 RGB 数据转换为 UIImage [英] iOS/Objective C: Converting RGB Data to UIImage

问题描述

我需要帮助将 24/32 位 RGB 原始图像转换为 uiimage.

i need help converting an 24/32 bit RGB raw image to uiimage.

我已经尝试过 Paul Solt 和其他人提供的示例，但没有任何效果.任何人都可以展示一个示例或教程吗?

I've tried the examples here from Paul Solt and others, but nothing work. Anybody could please show an example or tutorial?

图像数据保存在 nsdata 中，我想要一个 jpg 或 png 图像.

The image data is hold in nsdata and i would like to have a jpg or png image.

谢谢托尔斯滕

我正在使用 Paul Solt 的代码，它做了一些事情，但图像看起来像是一张图像中的图像信息的四倍.我不能在这里张贴图片:我在注释之间的方法开头添加了几行，现在它可以工作了:-)

I'm using the code by Paul Solt, it does something, but the image looks like it have four times the image information in one image. i cant post an image here: i added the lines at the beginning of the method between the comments, now it works :-)

+ (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *) buffer
                                withWidth:(int) width
                               withHeight:(int) height {

    // added code
    char* rgba = (char*)malloc(width*height*4);
    for(int i=0; i < width*height; ++i) {
        rgba[4*i] = buffer[3*i];
        rgba[4*i+1] = buffer[3*i+1];
        rgba[4*i+2] = buffer[3*i+2];
        rgba[4*i+3] = 255;
    }
    // 


    size_t bufferLength = width * height * 4;
    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, rgba, bufferLength, NULL);
    size_t bitsPerComponent = 8;
    size_t bitsPerPixel = 32;
    size_t bytesPerRow = 4 * width;

    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
    if(colorSpaceRef == NULL) {
        NSLog(@"Error allocating color space");
        CGDataProviderRelease(provider);
        return nil;
    }

    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;
    CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;

    CGImageRef iref = CGImageCreate(width,
                                    height,
                                    bitsPerComponent,
                                    bitsPerPixel,
                                    bytesPerRow,
                                    colorSpaceRef,
                                    bitmapInfo,
                                    provider,   // data provider
                                    NULL,       // decode
                                    YES,            // should interpolate
                                    renderingIntent);

    uint32_t* pixels = (uint32_t*)malloc(bufferLength);

    if(pixels == NULL) {
        NSLog(@"Error: Memory not allocated for bitmap");
        CGDataProviderRelease(provider);
        CGColorSpaceRelease(colorSpaceRef);
        CGImageRelease(iref);
        return nil;
    }

    CGContextRef context = CGBitmapContextCreate(pixels,
                                                 width,
                                                 height,
                                                 bitsPerComponent,
                                                 bytesPerRow,
                                                 colorSpaceRef,
                                                 bitmapInfo);

    if(context == NULL) {
        NSLog(@"Error context not created");
        free(pixels);
    }

    UIImage *image = nil;
    if(context) {

        CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, width, height), iref);

        CGImageRef imageRef = CGBitmapContextCreateImage(context);

        // Support both iPad 3.2 and iPhone 4 Retina displays with the correct scale
        if([UIImage respondsToSelector:@selector(imageWithCGImage:scale:orientation:)]) {
            float scale = [[UIScreen mainScreen] scale];
            image = [UIImage imageWithCGImage:imageRef scale:scale orientation:UIImageOrientationUp];
        } else {
            image = [UIImage imageWithCGImage:imageRef];
        }

        CGImageRelease(imageRef);   
        CGContextRelease(context);  
    }

    CGColorSpaceRelease(colorSpaceRef);
    CGImageRelease(iref);
    CGDataProviderRelease(provider);

    if(pixels) {
        free(pixels);
    }   
    return image;
}

推荐答案

解决方案:

我的位图图像数据只有3个字节，但是ios要4个字节，第四个是alpha.因此插入以下添加第 4 个字节的代码解决了问题.

my bitmap image data has only 3 bytes, but ios wants 4 bytes, the fourth is for alpha. so inserting the following code which added a 4th byte fixed the problem.

char* rgba = (char*)malloc(width*height*4);
for(int i=0; i < width*height; ++i) {
    rgba[4*i] = buffer[3*i];
    rgba[4*i+1] = buffer[3*i+1];
    rgba[4*i+2] = buffer[3*i+2];
    rgba[4*i+3] = 255;
}

这篇关于iOS/Objective C:将 RGB 数据转换为 UIImage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！