cmdline convert YUV 422p to JPG versus MagickWand api

goberhammer · Post by **goberhammer** » 2012-07-11T03:02:53-07:00

Hi all, first time poster

I'm, trying to implement a format conversion using MagickWand C api.
The source image is an YUV 422p 720x576 frame we get from a custom hardware.
The first part of the image contains all the Y components and the second part contains half U and half V components interlaced.

I can successfuly convert this image to any format using the below command line:

# convert -interlace plane -depth 8 -sampling-factor 4:2:2 -size 720x576 frame_442.yuv frame_442_cmdline.jpg

What I'm not able to do is implement the same conversion using C Wand api, because in the resulting image all the colors are wrong.
This is the code I'm using:

Code: Select all

#include <stdio.h>
#include <stdlib.h>
#include <wand/MagickWand.h>

#define ThrowWandException(wand) \
    { \
        char \
        *description; \
        \
        ExceptionType \
        severity; \
        \
        description=MagickGetException(wand,&severity); \
        (void) fprintf(stderr,"%s %s %lu %s\n",GetMagickModule(),description); \
        description=(char *) MagickRelinquishMemory(description); \
        exit(-1); \
    }

int main(int argc,char **argv)
{
    MagickBooleanType status;
    MagickWand *wand;
    double factors422[3] = { 4.0, 2.0, 2.0 };
    double factors211[3] = { 2.0, 1.0, 1.0 };

    if (argc != 3) {
        fprintf(stdout, "Usage: %s in.yuv out.jpg\n", argv[0]);
        exit(0);
    }

    MagickWandGenesis();
    wand = NewMagickWand();  

    status = MagickSetInterlaceScheme(wand, PlaneInterlace);
    if (status != MagickTrue) {
        ThrowWandException(wand);
    }

    status = MagickSetDepth(wand, 8);
    if (status != MagickTrue) {
        ThrowWandException(wand);
    }

    status = MagickSetSamplingFactors(wand, 3, factors422);
    if (status != MagickTrue) {
        ThrowWandException(wand);
    }

    status = MagickSetSize(wand, 720, 576);
    if (status != MagickTrue) {
        ThrowWandException(wand);
    }

    // No difference w/ or w/o
    //status = MagickSetFormat(wand, "YUV");
    //if (status != MagickTrue) {
    //    ThrowWandException(wand);
    //}

    // No difference w/ or w/o
    //status = MagickSetColorspace(wand, YUVColorspace);
    //if (status != MagickTrue) {
    //    ThrowWandException(wand);
    //}


    // convert -interlace plane -depth 8 -sampling-factor 4:2:2 -size 720x576 in.yuv out.jpg
    status = MagickReadImage(wand, argv[1]);
    if (status == MagickTrue) {
        size_t compression = 92;

        status = MagickSetFormat(wand, "JPG");
        if (status != MagickTrue) {
            ThrowWandException(wand);
        }

        status = MagickSetImageDepth(wand, 8);
        if (status != MagickTrue) {
            ThrowWandException(wand);
        }

        status = MagickSetSamplingFactors(wand, 3, factors211);
        if (status != MagickTrue) {
            ThrowWandException(wand);
        }

        status = MagickSetImageCompressionQuality(wand, compression);
        if (status != MagickTrue) {
            ThrowWandException(wand);
        }

        // No difference w/ or w/o
        //status = MagickSetInterlaceScheme(wand, JPEGInterlace);
        //if (status != MagickTrue) {
        //    ThrowWandException(wand);
        //}

        // No difference w/ or w/o
        //status = MagickSetColorspace(wand, RGBColorspace);
        //if (status != MagickTrue) {
        //    ThrowWandException(wand);
        //}

        status = MagickWriteImage(wand, argv[2]);
        if (status != MagickTrue) {
            ThrowWandException(wand);
        }

    }

    wand = DestroyMagickWand(wand);
    MagickWandTerminus();

    return(0);
}

Version: ImageMagick 6.6.9-7 2012-04-30 Q16

This is the source image: http://www.naustech.com/magick/frame_442.yuv
This is the correct result using command line convert: http://www.naustech.com/magick/frame_442_cmdline.jpg
This is the wrong-colors version using the C api: http://www.naustech.com/magick/frame_442.jpg

Any help would be really appreciated

Thanks in advance, best regards, Gabriele.