8 bit vs 16 bit to print labs

A photographer friend of mine processes everything in Photoshop in 16 bit
RAW. When he wants to have a print made he changes the image to an 8 bit
tif. He says that the reason for dropping to 8 bit is that most photo labs
have 8 bit printers.

It seems to me if you are going to switch to 8 bit for the print, you might
as well have never started in 16 bit in the first place. Don't you lose the
extra dynamic range, etc. as soon as you make the change? It doesn't makes
sense to me. What would happen if you sent a 16 bit file to be printed?
How much larger would the file size be - twice the size? Could the lab
process it?

 

I think 16 bit is only useful for if you are stretching color &
contrast, then it can be dumped.

 

16 bits doesn't give you greater dynamic range, it gives you more
colors *within* that range. Using 16-bit can protect you from
posterization when you make *big* adjustments. Reducing to 8-bit
after doing that makes sense; and he's right that labs generally want
the files in 8-bit format.

 

16 bits does give you more colors in that range, this will also help
you from posterization when making large adjustments, however you will
have to reduce to 8 bits for the lab. my personal opinion is to use 8
bits throughout your process.

all the very best
Dave

 

The reason you stay 16 bit as much as possible is so that as values
(brighness, color, contrast, etc.) are adjusted, there is deeper data to
draw from right out to the final version. eg, some changes will shrink
the dynamic range of a point, and there will be lower bits to "pull up"
in the LSB(s) of the more significant byte.

eg, a range of 0 to 255 has much less flexibility than 0-65535.

Once all your changes are made, clipping the lower bits off will not
show in printing which has a fairly narrow dynamic range.

Archive either the original or the pre-conversion to 8 bit version.


Don't you lose the

One of the places I print at only wants 8-bit files.
The other will take 8 or 16 bit, the later only on CD (not by net).

Cheers,
Alan