Compression - Decompressing JPEG to 48-bit ARGB

Author

Decompressing JPEG to 48-bit ARGB

Manhattan

2004-09-12, 3:55 pm

Hi,

I'd like to know if it's a good idea to decompress a 12-bit precision JPEG
to ARGB values with 16-bit per component. Is there a program that can read
such files ?

Thanks in advance.

Thomas Richter

2004-09-13, 8:55 am

Hi,

> I'd like to know if it's a good idea to decompress a 12-bit precision JPEG
> to ARGB values with 16-bit per component. Is there a program that can read
> such files ?

Frankly, I don't quite get the question. Whether this is a good idea
or not depends on what you want to do. In medical applications, 12 bit
output is more or less a requirement, and if your professional display
device uses 16 bits/component, then this is a very good idea indeed.

Surely there are jpg decoders that can read 12bpp files, and I would
call this a requirement for a codec that claims to be professional.

So long,
Thomas

Manhattan

2004-09-13, 8:55 pm

"Thomas Richter" <thor@cleopatra.math.tu-berlin.de> wrote in message
news:ci3lfm$1eb$1@mamenchi.zrz.TU-Berlin.DE...
> Hi,
>
JPEG[color=darkred]
read[color=darkred]
>
> Frankly, I don't quite get the question. Whether this is a good idea
> or not depends on what you want to do. In medical applications, 12 bit
> output is more or less a requirement, and if your professional display
> device uses 16 bits/component, then this is a very good idea indeed.
>
> Surely there are jpg decoders that can read 12bpp files, and I would
> call this a requirement for a codec that claims to be professional.
>
> So long,
> Thomas

I realized I can't count. It's not 48-bit but 64-bit XRGB : 16-bit per
sample. X is unused.
This is for a personal project. I don't have access to any special device to
display the image. I read that Photoshop can read 48-bit RGB but I don't
know if there is a program to read 64-bit RGB.

Nils

2004-09-13, 8:55 pm

"Manhattan" <manhattan95@wanadoo.fr> wrote in message
news:ci4vv1$adf$1@news-reader5.wanadoo.fr...
> I realized I can't count. It's not 48-bit but 64-bit XRGB : 16-bit per
> sample. X is unused.
> This is for a personal project. I don't have access to any special device
to
> display the image. I read that Photoshop can read 48-bit RGB but I don't
> know if there is a program to read 64-bit RGB.
>
>

At least these are not standard bitmaps in the Windows GDI sense. The
standard DIB's highest bits/pixel is 32bit, for RGBA.

I have experimented a bit with more precision per channel, esp. since new
digicams store pixels with 12, 13 or 14 bits per channel. You'd have to read
the raw or TIFF images though, I haven't yet encountered one that produced
JPEG files with higher than 8bit/channel precision. I don't know JPEG too
well, but I think it is limited to that.

You could have a look at TIFF, which is able to do it, or create your own
format.

Kind regards,

Nils

Thomas Richter

2004-09-14, 3:55 am

Hi,

> I realized I can't count. It's not 48-bit but 64-bit XRGB : 16-bit per
> sample. X is unused.
> This is for a personal project. I don't have access to any special device to
> display the image. I read that Photoshop can read 48-bit RGB but I don't
> know if there is a program to read 64-bit RGB.

I'm not sure which program would be able to display this either. I would
also believe photoshop can do it, but in case this is just some kind of
"toy project", I would rather suggest to store the decompressed images
as "raw" bitmap and write a custom viewer for it that allows you to extract
parts of this image; one thing we did when we had to deal with 16bpp medial
image data was to allow the user some kind of "luminance window". Pixels
with a higher or lower luminance are shown as complete black or white.
Kind of allowed you to "move" thru the image in the luminance direction.

So long,
Thomas

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