manual white balance vs. photoshop

[fdog]

If you WB at depth, you might at least have a shred of a red channel to play with later. Otherwise, you'll have to "make" one, a PITA.

Assuming you're strobeless.

All the best, James

 

[Charlie99]

Ok, here's a question from a non-digital camera person BUT a person who has and does white balance broadcast video cameras for TV production. How can you correct a color if you do not know what the color is??? If you took a picture at the start of the dive of a white card, at depth, then you have a VALID reference point to correct the colors, otherwise you are guessing, right?

The purpose of white balancing a camera is to "define" white for the electronics in the camera. In fact, we MUST do both a white and black balance before a camera should be used.

The CCD already know what the black settings (aka offset or zero levels) are. All that is left to figure out is the RGB gains. If you tell the camera that something is white, then it will adjust gains to get equal output levels. Underwater, this mostly results in cranking up the gain on the red channel waaaaay up.

My point and shoot doesn't have white balance, but by looking at photos of bright white sand I can see that ideally the red channel gain would be 3 or 4 times higher. I can crank up the gain in Photoshop Elements, but since my max red pixel value is only 50 or so (out of 256 max), I effectively only have 5 or 6 bits of red channel resolution rather than 8.

 

[mtiffee]

When you manually white balance, you tell the camera to adjust it's color levels on the CCD during the CAPTURE process. It will boost the red levels coming in, allowing the camera to capture more of the red information. Then, when you correct in Photoshop you have more of the red color information to correct with. If you do an auto white balance, you don't have that red information to play with and there is no way to artifically create it, other than paint it on. Garbage in - Garbage out.

ALWAYS manually white balance when you're not using a strobe, unless you want that blue look for effect.

I'm an Emmy award-winning TV editor, now I do live productions for ABC Sports. We used to get blue footage in from shooters who didn't white balance correctly, or at all, and there really isn't any way to fake it. If the colors not there during the capture process.. oh well.

 

[fdog]

mtiffee, plate blending is an obscure technique that allows a red channel to be built from nothing. It is time consuming, though.

I believe the talented R. Delfs published an article refering to the use of plate blending for regeneration of a non-existant red channel.

Granted it's not what was there to begin with, but it is a great way to salvage a shot of high value.

All the best, James

 

[fdog]

This photo of me was shot by a friend during our last trip, where I was wowed by my film results. The camera he used was a Sony of some flavor, cheap housing, no strobe. Depth was 60 fsw, 50% overcast.

The first image is unedited. The red channel for this image was nonexistant, with the exception of a tiny bit on the dome reflection. You can see this in the second image.

After splitting the channels, I imported some of the green and blue into the red, and combined them.

The results are in the final image. Quite an improvement! Since this is on my profile page, maybe I should replace it, come to think, since I did all the work.


All the best, James

 

[mtiffee]

Yeah, I'm familiar with this.. I used it before I discovered the results of manual white balance. It does improve the photo, but it's still nothing close to capturing the image with corrected white balance. The pictures I took on my last trip turned out incredible.. In fact, I just finished framing about 10 8x10's. It looks like I took them at 10 feet, when it was actually more like 45-50 feet!

Here's some posted throughout this thread here: http://www.scubaboard.com/t59135.html

 

[Scubatooth]

alot of good advice has been said here and fdog said it best about the red channel. there is a way to adjust the color tempature in PS but it requires that you entire system is color calibrated and profiled (monitors, scanners,cameras, printers or other output media). The other things is that it is a total pain and it takes forever to do it (ie i had and image that the person had set the image to tungsten balance in a indoor enviroment which put a yellow cast. i was able to finally get rid of it with the use of curves, contrast, hue & saturation adjustments and i cant remeber what else. anyways like its been said and this is how i operate. white balance all the time and act like PS doesnt exist so to cut down on your editting time and increase the enjoyment of your prints

FWIW

Tooth

 

[mannydib]

wow, i learned even more than i thought i would.
thanks for all the help guys!

i cant wait to get back into digital uw photo again.

anyone think theres a chance of repairing a flooded camera? or should i just replace it and move on.