[APML] A Curves Exercise [was: Histograms, curving and layers]

[Matt BenDaniel <matt@starmatt.com>]

Alan,

The most important skill to master in image processing is curves. By far, you'll get more bang out of curves than any other tool. Both Photoshop and PictureWindow have good curves tools.

I made an exercise for you (and anyone else who might be interested). 

I place an uncurved image of Central Auriga on my web site. Save the uncurved image onto your disk. Using solely a curves layer, try to make the color balance and contrast of the uncurved picture look like my curved one. All you need concern yourself with at this point is adjusting the R, G, and B curves in a single adjustment layer. That's it. I already took care of stacking, AV-ing and star shaping the uncurved image, so you don't need to worry about any of that with this image.

Now, I don't claim that this exercise is easy. But if you do it right, you should be able to make the uncurved image look just like the curved one on my web page.  The link to the uncurved image is at the bottom of the page:

http://starmatt.com/gallery/astro/central_auriga.html

I hope this exercise is helpful to you and others. Please let me know if you have questions, problems or have results to share.

Matt

At 17:45 04-12-02 -0800, Alan Voetsch wrote:
>Hi Matt,
>
>--- Matt BenDaniel <matt@starmatt.com> wrote:
>> Thanks. I'm always looking for suggestions for more
>> articles.
>
>How about: making a copy to work on, setting black
>points (whatever that is), making or using layers. All
>I feel partially proficient at is adjusting contrast,
>lightness and watching how much the image changes as I
>move the curves slider around. 
>
>> The order matters a lot. If one layer clips the
>> image, nothing above it in the layer stack will
>> rescue the lost info. I find that an AV layer works
>> best if it is right above the source layer. When
>> doing AV, I'll alternate adjustments to the AV layer
>> and to the main curves layer. Their adjustment is
>> intertwined.
>
>I understand the concept, but this sounds like there
>are a lot of ways to learn a lesson the hard way.
>Maybe another article on the sequential steps to use
>throughout the whole process.
>
>Thanks Matt,
>Alan

--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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