[HUG ] Re: IMG: Triptych

Hi Karl,

> I'm not sure how to answer your questions technically, but I just
> finished a
> shoot that was at least 2 stops overexposed.  The raw files contained more
> information than was in the image, and I was able to pull that info out of
> the file.  I could not begin to pull that same data out of the .jpg files
> produced concurrently.

I don't doubt that.  Typically, JPEGs are lossy, and have the setpoints and
tonal curves set, so that does not surprise me.  It was TIFF files I was
specifically questioning, and more so scanners than cameras.

> .tif files are lossless, but the camera's internal settings (usually
> changeable by the user) choose the amount of sharpening, the
> contrast, etc.
> to produce the .tif (or .jpg) image you take out of the camera.

Understood.  That's implementation dependant though, not a property of TIFF.
A TIFF file could have none of that done, and still be a TIFF file.

> That's why raw files are so much larger than .tif files.

Actually, raw files should be smaller than an uncompressed TIFF of the same
image.  The TIFF typically has full color data for every "pixel".  Say the
camera has 16 bits/color, therefore each "pixel" would be 48 bits (16 bits
times 3 colors/pixel).  The raw file would only have 16 bits per "pixel",
since each "pixel" of the sensor only contains one of the three colors.

If the raw files are larger, then they probably have had Bayer Pattern
reconciliation done, and store in 16 bits/color.  Where the TIFF may be 8
bits/color.  Any implementation can do things entirely different.

My only point was, there is no requirement for a TIFF to not be able to
contain full raw data, and it is fully capable of it, especially in a
scanner.  In a camera, it is a different story.  A scanner does not do Bayer
Pattern reconciliation.  A camera does, so the "raw" files are different.

None of my scanners save data as "raw" per se.  To save as "raw" you save it
as a lossless TIFF file.

Regards,

Austin


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