Hi

I hope someone can help me, while colour correcting images I always have trouble selecting a midtone to see if there is any colour cast present. I always do my highlight and shadow areas with no trouble using the numbers method but then have trouble selecting what I think is the midtone, any surgestions?


Thanks
:depressed

What a great question digi! I wish I could answer it, but I have the same problem you do. I'll be watching the replies here hoping we can both be enlightened! ;)

Jeanie

I guess I'm retarded because I don't use and fancy techniques. In PSP there are some very good auto filters. One for fade and color cast, one for contrast, one for color correction using the numbers, one manual one that is outstanding, you select an area of skin and choose between about 20 different shades of human skin, and it does water, sky, fruit, etc.
I never use channels unless I'm doing something really unique. I'm sure Jac would say, this guy's nuts, but my results are pretty good.

It's not obligatory to set a midtone. Generally any gray will do. Plus you can reset the midtone dropper to another value, such as skintone by doubleclicking on it.

Hi Digi :)

I never set the midtones. I was taught (hopefully correctly) that if you set the white and black points, the midtones should fall where they belong...

Originally posted by fugitive
I'm sure Jac would say, this guy's nuts, but my results are pretty good.

Awww, Greg.... I would never say that.... :devil:

Colour correction - what a deep topic to attempt to discuss in a web forum! I will attempt to give this my best shot. [g]

Endpoints - Not all images will have both endpoints or will require that the endpoints be neutral, but many images will - and these images will greatly benefit from setting neutral endpoints, tones throughout the image will often be more pure after this step. But this does not mean that you can't do better...

Neutrals - If an image has a known neutral, then it should usually be made neutral and the rest of the image will usually benefit. This could be any tonal value that should be neutral - not just a 'mid' gray point.

Known Memory Colours - Skintones, blue skys, green grass and a ripe red tomato are common examples.

The first stage in colour correction is understanding the job brief - are we attempting to 'match the art' or improve upon it? Next comes image evaluation - what are the existing colour/tonal values for endpoints (highlights/shadows), known/presumed neutrals and key memory colours? Next apply separate curves or levels to each channel to bring the existing values into the required values. This is often done for four key image areas using one set of curves which address endpoints/neutrals/memory colour. Finally selective colour correction can be applied to key areas of the image, if they still need attention after the global edits.

I have an article at my site on how to use info palette readings of all colour modes (RGB, LAB, HSB and CMYK) to aid in image assesment and editing:

http://members.ozemail.com.au/~binaryfx/ST_colourevaluation.html

Now for some links to further reading on colour correction...

For anyone who is serious about colour - I would STRONGLY suggest you look into the works of Dan Margulis:

http://www.ledet.com/margulis/PP6_Chapter2.pdf

Perhaps look into this tutorial on curves if the above PDF does not make much sense:

http://www.gurusnetwork.com/tutorials/photoshop/curves1.html

A levels correction method, by the numbers similar to curves:

www.eddietapp.com/PDFs/ccmethod7.pdf

Another one on curves (including neutrals)

www.adobeevangelists.com/pdfs/photoshop/tipsandtricks/CorrectByNumbers.pdf

Here is another one which is good too:

http://members.aol.com/clehan/tips/colorcx.pdf

And a couple from creativepro:

http://www.creativepro.com/story/feature/13486.html

http://www.creativepro.com/story/feature/13811.html

And here is some info on colour perception and memory colours (memory colour is a common prepress and scanning term):

http://www.execpc.com/~rbean/color/color4.txt

http://www.execpc.com/~rbean/color/

Regards,

Stephen Marsh.

Some nice links there and certainly food for thought. Thanks:)

Wow - that's some reply Stephen! Thanks for all the info a great links. Looks like I have some studying to do! :D
Jeanie

Thank you all for your replys, and a big thank you to Stephen, your hard work on my behalf will benefit alot of visitors to this forum. There is so much to read from your links that I'am sure I will find what I'am looking for("I think their is a song title in there someware") , one of the links listed is one I have used to learn how to get ride of a colour cast with the numbers and that was:-www.adobeevangelists.com/pdfs/photo...ctByNumbers.pdf.
Again thanks alot:D

Digi