RAW vs White balance

Started Nov 20, 2006 | Discussions thread
Jonas B Forum Pro • Posts: 14,596
Re: Unequivocal evidence - here too now

In a reply to Gordon CurtisR wrote:

-snip
Um.. no. The WB is done pre-raw for preset WB as well. Go back
and look again. I just did it with manual to show it very clearly
(and demonstrate one potential practical use.) If you test with a
brightly exposed target, the difference in preset WBs is clear as
well - the russian guys show it well (and if you look closely at
JonasB's shots it's clear too.)

I missed that. I was a little sloppy and didn't take the linear x-axis into account, at least not as much as I should have done. Looking at the first 15 pictures I just assumed that my shytter isn't exact, causing minor exposure shifts.

In my second try with two different targets I overexposed 1 stop to make the x values more spread out. I probably could have increased the exposure even more.

Again: Curtis directing himself to Gordon:

I'm not sure what you're saying, but it seems clear to me that
sensitivity up to, and including 800 are done without bit shifting
(or you'd see black stripes in the histograms as you do at 1600 and
3200).

In my first set of 3*5 pictures I got black stripes also in the ISO800 pictures.

Again, I'm grateful that you showed us the last three pictures Curtis. They made me look again and make that second try.

To get a final and clear picture of what is going on at the pre AD stages I guess one would have to make some different series of at least two different targets, at all white balance presets and with manual balancing, at all ISO values. (No, I'm not prepared to do that.)

What does it all matter with regards to real photos? That is the important question to me. Sometimes I get very good colors, sometimes not. As I have my own profile for ACR it works fine. I have the white balance set to sunshine all the time except for some times when I have choosen to make a manual balance. I never thought of the possibly need for another profile at those occassions. Then I sometimes got colors a bit off but I think I just blamed the light for this.

As pictures files in raw format have to be converted to something else to let us look at them the raw converter is very important. This make for another tedious set of tests: We don't know if ACR, Capture One and Silkypix takes this into account. Heck, we even don't know if the Pentax software handles the files correctly.

Suddenly there are several questions.

Very interesting. It was easier when I still believed that raw was raw. That is until yesterday... New knowledge is good though and just being aware of this will help to get "critical" pictures better in the future.

-- hide signature --

regards,

Jonas

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