Luminescent results from auto levels adjustment?

[Idoc]

Posted this in the Sharing Photos section and got no responses maybe someone here can help me.

Normally after I convert from raw, I go to PS and do image sizing and some auto adjustments: levels & color.

This little yellow flower gave me some results I've never seen before after an auto adjust levels.

This is near what the original image looked like: :) :) :) :)
http://images.fotopic.net/?id=3410164&outx=600&noresize=1&nostamp=1

After the auto levels: :shock: :shock: :shock: :shock:
http://images.fotopic.net/?id=3410165&outx=600&noresize=1&nostamp=1


Does anyone know what I picked up traces of, or why it would do this?

[w10d]

This is the sort of problem you can run into when using an 'auto' feature. Take a look at each colour channel; R and G have a range of tones, but the B channel is very dark. Auto Levels doesn't know what you have photographed, but assumes a 'normal' image - which would have some light values in the B channel. It has therefore tried to lighten the lightest parts of the B channel, giving the odd blue 'highlights'.

If you use 'manual' Levels, and drag the right triangle to the end of the B channel histogram you'll get a similar effect: If you continue to drag the slider the image will become bluer in progressively darker areas.

Hope that all makes sense, if not, have a good play with the options in the Levels dialogue box....(Using Auto Levels and Colour is a bit like shooting everything on Auto camera modes - works most of the time).

[dtrayers]

As stated above, sometimes you can get good results from the Auto features (I like to try Auto Color), but usually your better off making the adjustments yourself.

Here's your first photo again and I adjusted the center slider in the Levels adjusment to the left a little so the midpoint value is 1.5:

http://home.comcast.net/~dtrayers/photos/Yellowflower1-2.jpg

Since your using PS, you'd be best if you made all the adjustments in layers so you can easily change them later. You could even adjust each color in it's own layer for really tricky images.

[Idoc]

w10d: Thanks so much for the simple explanation, that helps a lot. I'll continue to experiment when using the levels to try out what you described.

dtrayers: So a simple levels adjustment of the middle slider did that, I think I might try manual levels from now on to adjust. The results you got were better than anything I expected to see.

:D Thanks guys, this is eye opening :shock: and not because I just woke up.

[maderito]

Interesting thread and good comments from all. I had an additional thought about the image which leads to different approach to color correction.

The blue cast in the leaves of the original image results, in part, because of the different "temperatures" of the sunny and shady parts of the image. The white balance for the image appears to be set OK for the yellow petals and the bright portions of the leaves which are warm. However, shadowed areas are consequently too cool are thus the blue color cast.

In Photoshop, I copied a selection of the dark green in the shaded leaves to a new layer, "warmed" it by decreasing blue and increasing red with curves, applied a Gaussian blur, overlayed it on the original image, and set the blending mode to color. The result warms up the shaded leaves which removes the blue cast.
http://display.lifepics.com/imgdisp.asp?filespec=%60foxhx2cuxmwdogx%5D9%3C%3D8 %3B9dOjeOrmlfitq%7Cfy7ptq%0C8289%3F%3E%0F4%3A3828

[Idoc]

Maderito: Wow! Great idea and use of the layers, All it takes is a little thought to go a long way. What you described perfectly illustrates that technique and I can really tell the difference.

Thanks for the great tips guys! :) :D

[PacAce]

In case you missed my reply in "Share Photos":

http://www.photography-on-the.net/forum/showthread.php?t=27993