How does in camera optimization (contrast, saturation, etc.) work?

[dave_raines]

This is sort of a technical question, I guess, so bear with me as I try to

express what I'm really asking.

 

I shoot with a Nikon D50, but I don't think it matters. And the reason I'm

asking the question is for shooting panoramas to stitch together, how do I get

the color/luminosity to exactly match up (in .jpg)? If I set the camera in

manual, with the same exposure, same (non auto) contrast, saturation, Hue

adjustment settings, should this mean that the color (say, the same spot in the

sky) match up exactly?

 

On a technical level, how does the contrast done in camera really work? If it's

on "normal (0)" contrast, does it apply a curve that will take each pixel

brightness to another brightness based only on that pixel only, or does the

brightness level it's taken to depend on that pixel and on the rest of image?

The same (approximate) question could be asked for saturation.

 

I hope this question made sense, because it's something that I've been trying to

figure out for a while.

And before anyone says it, yes, I know I could shoot in raw and do it all

manually on the computer.

[ellis_vener_photography]

Different cameras likely work differently but my overarching assumption is that all of the values for wevery pixel are considered.

 

So if for some reason you are compelled (compelled: as in someone is holding a gun to your head or the head of your spouse or child) to shoot JPEGS for photos that will be montaged together into a panoramic view I would definitely zero out all in-camera processing settings.

[godfrey]

Focus, sensitivity (ISO), exposure time, lens opening, and noise reduction settings

are the fundamentals. These settings affect the RAW files, along with whatever

other implicit massaging of the RAW data might be done in the chain from sensor

through capture buffer and A->D converter to RAW data file containing sensor data

stored on a memory card.

 

Sizing, white balance, contrast, sharpness, saturation, white balance, etc are all

image processing settings applied to the RAW data, inserted at the end of the above

data handling chain just prior to writing to the memory card. They are applied during

a RAW conversion transformation just prior to the JPEG compression, just as if you

took the RAW file into Photoshop, made a few edits to these parameters, and output

the finished product as a JPEG file.

 

So, to obtain a consistent color balance and exposure across a multi-frame capture

intended for panorama processing, you switch the ISO to a manually fixed setting,

set the metering to manual and set the proper exposure for the scene, and set the

focus manually. That makes sure the camera captures a consistent set of RAW

image files across the scene. You set the white balance to one of the fixed settings,

set the contrast/saturation/sharpness/color tone to a set of fixed settings, and the

camera will output JPEGs to those fixed image processing settings.

 

This makes as consistent a set of JPEG output files as your camera can for

panoramic stitching. The basic message is to turn off ISO, exposure automation and

white balance processing to obtain maximum consistency.

 

Godfrey

[SteveH]

A really excellent summary by Mr. DiGirogi above. I would add that a good way to

establish your exposure is to set the camera first on aperture priority and select the

aperture you want. Watch the shutter speed as you pan across your intended subject.

Then set the shutter speed manually based on your estimate of the one between the

fastest and slowest. I generally use evaluative metering, but you could also spot meter

the scene to establish the best exposure.

[dbcooper]

To condense what Godfrey so accurately said, in-camera processing basically works the same as post-processing on a computer, although it's not as sophisticated. The in-camera processing will definitely have an effect on all file formats except RAW, where it should have no effect at all.

 

There will be some variation in the output result of in-camera processing as you move it about to take multiple frames for stitching, especially the color saturation if set to a stronger amount than 'normal'.

 

So for the smoothest stitching, you'll want to defeat the potential for any variation in the images. The easiest way to do that? Shoot camera RAW. Or, at least turn off all in-camera processing, and shoot in manual mode. It is especially important that you do not vary the lens aperture and focus for images that will be stitched/combined.