16-bit to RAW and back…

PE
Posted By
phoney.email
Mar 2, 2004
Views
367
Replies
4
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Closed
Photoshop 6.

I have a 16-bit image with 4 channels, RGB + an alpha channel (IR data). I save this as RAW. So far so good. I massage this RAW data with a program I have written.

However, when I import the RAW file back and specify 4 channels, PS 6 *assumes* this 16 bit image is CMYK – which it is *not* – and gives me no choice in the matter!

How do I convince PS 6 to import this RAW 16-bit image with 4 channels as RGB + Alpha?

Also, PS 6 won’t let me manipulate (delete, add, copy, change, etc) 16-bit channels, right? The idea is to save them individually and then combine later manually.

Thanks!

Don.
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CC
Chris Cox
Mar 2, 2004
In article , Don
wrote:

Photoshop 6.

I have a 16-bit image with 4 channels, RGB + an alpha channel (IR data). I save this as RAW. So far so good. I massage this RAW data with a program I have written.

However, when I import the RAW file back and specify 4 channels, PS 6 *assumes* this 16 bit image is CMYK – which it is *not* – and gives me no choice in the matter!

How do I convince PS 6 to import this RAW 16-bit image with 4 channels as RGB + Alpha?

You don’t.
But after you import it, you convert to multichannel, then to RGB.

Also, PS 6 won’t let me manipulate (delete, add, copy, change, etc) 16-bit channels, right? The idea is to save them individually and then combine later manually.

You really need to upgrade to Photoshop CS.

Chris
PE
phoney.email
Mar 3, 2004
On Tue, 02 Mar 2004 23:56:30 GMT, Chris Cox
wrote:

Photoshop 6.

How do I convince PS 6 to import this RAW 16-bit image with 4 channels as RGB + Alpha?

You don’t.
But after you import it, you convert to multichannel, then to RGB.

Multichannel option is disabled here in 16-bit mode (Photoshop 6).

Anything else I can try?

Also, how do I calculate the size of a TIFF header? PS 6 seems to append a variable length footer which makes it difficult to figure out (i.e. the simple formula "header = tif size – raw size" doesn’t work).

What I’m getting at is "preserve header" option when saving raw files.

Thanks!

Don.
CC
Chris Cox
Mar 7, 2004
In article , Don
wrote:

On Tue, 02 Mar 2004 23:56:30 GMT, Chris Cox
wrote:

Photoshop 6.

How do I convince PS 6 to import this RAW 16-bit image with 4 channels as RGB + Alpha?

You don’t.
But after you import it, you convert to multichannel, then to RGB.

Multichannel option is disabled here in 16-bit mode (Photoshop 6).
Anything else I can try?

Also, how do I calculate the size of a TIFF header? PS 6 seems to append a variable length footer which makes it difficult to figure out (i.e. the simple formula "header = tif size – raw size" doesn’t work).

You can’t – TIFF headers are not fixed sizes.
The TIFF format needs to be parsed to read it correctly.

Chris
PE
phoney.email
Mar 7, 2004
On Sun, 07 Mar 2004 03:05:54 GMT, Chris Cox
wrote:

Multichannel option is disabled here in 16-bit mode (Photoshop 6).
Anything else I can try?

Also, how do I calculate the size of a TIFF header? PS 6 seems to append a variable length footer which makes it difficult to figure out (i.e. the simple formula "header = tif size – raw size" doesn’t work).

You can’t – TIFF headers are not fixed sizes.
The TIFF format needs to be parsed to read it correctly.

The problem is Adobe seems to add a footer as well and it refuses to read a TIFF file without it. You folks seems to have thought of everything to prevent us loading 4-channel 16-bit RGB files! 😉

Anyway, since multichannel option is disabled here in 16-bit mode (Photoshop 6) anything else I can try?

I mean, I can always use a hex editor and cut and paste headers and footers to my RAW file (same image size) but that’s very clumsy especially while I have this dedicated graphics program here. So, the preferred option is to use PS.

Don.

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