Question

我正在试图弄清楚如何使用CMYK颜色空间创建一个bitmapcontext并将图像绘制到其中。

我正在使用Apple的Q＆amp; A here中的代码，并将其修改为创建CMYK色彩空间并绘制到其中。在我的日志中，我收到错误

不支持的像素描述 - 4个组件，每个组件8位，每像素32位

我返回了一个null上下文。

我错过了什么？这是我正在尝试运行的代码：

CGContextRef    context = NULL;
CGColorSpaceRef colorSpace;
void *          bitmapData;
int             bitmapByteCount;
int             bitmapBytesPerRow;

// Get image width, height. We'll use the entire image.
size_t pixelsWide = CGImageGetWidth(inImage);
size_t pixelsHigh = CGImageGetHeight(inImage);

// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 
bitmapBytesPerRow   = (pixelsWide * 4);
bitmapByteCount     = (bitmapBytesPerRow * pixelsHigh);

// Use the generic CMYK color space.
colorSpace = CGColorSpaceCreateDeviceCMYK();
if (colorSpace == NULL)
{
    fprintf(stderr, "Error allocating color space\n");
    return NULL;
}

// Allocate memory for image data. This is the destination in memory
// where any drawing to the bitmap context will be rendered.
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL) 
{
    fprintf (stderr, "Memory not allocated!");
    CGColorSpaceRelease( colorSpace );
    return NULL;
}

// Create the bitmap context. We don't need alpha.  Regardless of what the source image format is 
// (CMYK, Grayscale, and so on) it will be converted over to the format
// specified here by CGBitmapContextCreate.
context = CGBitmapContextCreate (bitmapData,
                                 pixelsWide,
                                 pixelsHigh,
                                 8,      // bits per component
                                 bitmapBytesPerRow,
                                 colorSpace,
                                 kCGImageAlphaNone);
if (context == NULL)
{
    free (bitmapData);
    fprintf (stderr, "Context not created!");
}

// Make sure and release colorspace before returning
CGColorSpaceRelease( colorSpace );

return context;

提前致谢！ -Syu

Answer 1

iPhone OS上没有CMY位图上下文。但也没有关于iPhone支持哪些像素格式的文档only for Mac OS。这是反复试验：（

是否可以使用CMYK颜色空间创建CGBitmapContext并绘制到其中？

1 个答案: