Dealing with MONO12 images in memory

(Trying this again since my last attempt to email the list seems to
have disappeared...)

Hello

I am new to Graphicsmagick and this list.

I'm using the graphicsmagick libraries with C++ on a Redhat linux
machine.

I have a program which captures images from GigE cameras using
Aravis libraries. I've been doing this successfully with images
in formats they call MONO8 and MONO12 for a while. Now I would
like to take advantage of Graphicsmagick to deal with other
formats (e.g. RGB8, BayerRG8, YUV422Packed...), get some loss-less
image compression, write files in different formats, etc., but I'm
running into a few problems. Hopefully, I'm missing something
simple?

Maybe this code snippet will be enough to show what I am talking
about:

Blob blob(pRaw16Image, (arv_width * arv_height *
nbytes));

printf("Blob data: 0x%x, length: %ld\n",
blob.data(), blob.length());

Image gmimage;

gmimage.read(blob, Geometry(arv_width, arv_height),
16);

gmimage.type(GrayscaleType);

// gmimage.magick("MONO12");

printf("gmimage.isValid: %d\n", gmimage.isValid());

gmimage.display();

if((Filename != NULL) && (strcmp(Filename,
"none") != 0)) {

printf(1, "writing file: %s\n", Filename);

gmimage.write(Filename);

}

pRaw16Image points to data which I know to contain grayscale data
represented in two bytes per pixel which I've been able to
manipulate/display using other code. nbytes is two in this
example.

Not sure about the proper use of the 3rd argument in the
image.read() function - I've tried both 16 and 2.

The commented out image.magick("MONO12") was a shot in the dark
that compiled o.k. but didn't do what I hoped.

gmimage.display() pops up a window that is the right size, but is
empty/black. The image info for the window says

Image:

Format:

Geometry: 1292x964

Class: DirectClass

Type: bilevel

Depth: 1 bits-per-pixel component

Channel Depths:

Gray: 1 bits

Channel Statistics:

Gray:

Minimum: 255.00 (1.0000)

Maximum: 0.00 (0.0000)

Obviously I am wrong on depth, min, max

I've tried several different file extensions on Filename. With
output like this:

for jpg:

width : 1292

height : 964

bpp : 16

format : MONO_12 (0x1100005)

Blob data: 0xee39f008, length: 2490976

gmimage.isValid: 1

writing file: gmimage3.jpg

terminate called after throwing an
instance of 'Magick::ErrorCoder'

what(): Magick: Application transferred too
few scanlines (gmimage3.jpg) reported by coders/jpeg.c:345

(JPEGErrorHandler)

Magick: abort due to signal 6 (SIGABRT) "Abort"...

for tiff:

terminate called after throwing an instance of
'Magick::ErrorCache'

what(): Magick: Pixel cache is not open
(gmimage3.tiff) reported by magick/pixel_cache.c:825
(AcquireCacheNexus)

Magick: abort due to signal 6 (SIGABRT) "Abort"...

for png

terminate called after throwing an instance of
'Magick::ErrorCoder'

what(): Magick: No IDATs written into file
(gmimage3.png) reported by coders/png.c:1084 (PNGErrorHandler)

Magick: abort due to signal 6 (SIGABRT) "Abort"...

Hopefully this is readable, and you'll be able to tell me I've
missed something basic. The size is right, but I obviously don't
understand proper formatting of either the blob or the image.

Thanks in advance for any help you might offer.

Rob

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