将ImageMagick命令转换为iOS

Question

我正在尝试将以下ImageMagick命令转换为objective-c：

convert photo.png -posterize 6 photo2.png

我基本上只是想尝试一些UIImage并将简单的posterize效果应用于它。我写了下面的代码，它对图像没有任何影响。它不会抛出任何异常或失败。我有一个惊慌失措，我要么搞砸命令参数或图像输入/输出。有没有人对如何解决这个问题有任何建议？

MagickWandGenesis();
MagickWand *wand = NewMagickWand();
NSData *data = UIImagePNGRepresentation(self.originalImage);
MagickReadImageBlob(wand, [data bytes], [data length]);

int arg_count = 2;
char *args[] = { "-posterize", "6", NULL};

ImageInfo *image_info = AcquireImageInfo();
ExceptionInfo *exception = AcquireExceptionInfo();

MagickBooleanType status = ConvertImageCommand(image_info, arg_count, args, NULL, exception);

if (exception->severity != UndefinedException)
{
    status = MagickTrue;
    CatchException(exception);
}

if (status == MagickFalse)
{
    NSLog(@"FAIL");
}

self.imageView.image = self.originalImage;

image_info=DestroyImageInfo(image_info);
exception=DestroyExceptionInfo(exception);
DestroyMagickWand(wand);
MagickWandTerminus();

Answer 1

我相信你正在寻找Imagemagick的MagickPosterizeImage。

MagickWandGenesis();
MagickWand *wand = NewMagickWand();
NSData *data = UIImagePNGRepresentation(self.originalImage);
MagickReadImageBlob(wand, [data bytes], [data length]);

MagickBooleanType = status;

status = MagickPosterizeImage(wand,6,MagickFalse);
if (status == MagickFalse)
{
    NSLog(@"FAIL");
}

// Convert wand back to UIImage
unsigned char * c_blob;
size_t data_length;
c_blob = MagickGetImageBlob(wand,&data_length);
data = [NSData dataWithBytes:c_blob length:data_length];
self.imageView.image = [UIImage imageWithData:data];

DestroyMagickWand(wand);
MagickWandTerminus();

还有MagickOrderedPosterizeImage & MagickOrderedPosterizeImageChannel来微调抖动阈值和目标颜色通道。