Dynax Digital Forums

Correction of Colour Casts

Now the following are two methods to remove colour casts- which one works better depends often on the image and you should try both!

(1) open image > layer > new > layer > edit > fill > use 50% grey > OK > set layer blending mode to difference > layer > new adjustment layer >threshold > OK > drag slider all to the left- the image will become white > slowly drag the slider back to the right- the first areas that appear are the neutral midtones > hold the shift key and move your cursor exactly over that first point and click in the image > click cancel in the treshold dialogue box > drag your grey layer 1 in the layers palette to the rubbish bin- you don't need that one anymore as you have found the point in your image that "should" be neutral grey > open: levels or curves > chose the midtone eyedropper (the one under options in the middle) and click where you have left the colour sampler tool point in your image- this should remove all colour casts

Problem

Sometimes there is no neutral grey in your image- than do the following: (or you can try both versions and see what works better)

(2) open you image > layer > new adjustment layer > threshold > OK > move the slider all the the left and then slowly to the right > click with the shift key hold down on the first point that appears > now move the slider all to the right and slowly from that position back to the middle > when the first points appears > shift click again > once you have set both markers click "cancel" in the threshold dialogue box. You now have two markers in your original image that are the darkest and the lightest points in your image > open levels/ curves > chose the black point eyedropper and click in the darker marker and do the same with the white point eyedropper.

Both of the above methods work usually quite well in eliminating any colour casts- but not always as usual.

(3) one last thing to try: open your image > choose the eyedropper tool and click somewhere in your image where you know that point should be white. Then: > layer > new > layer > edit > fill >foreground colour > image >adjustments > invert > lower the opacity of this layer to somewhere around 10 - 20% and set the blending mode to either colour or hue

Hope this helps!
 Stef.

Remedy for shooting through glas also: a good way to improve midtone contrast

open image > copy the background layer > apply unsharp mask with the following settings: amount: 40%; radius 30 pixels; threshold 0

This should eliminate the haze created by shooting through glass and is generally a good way to improve midtone contrast. Play around with the settings a bit but keep the radius high. If it is too strong you can always lower the opacity of the duplicated background layer.

Stef.

Question:
why would you copy the background layer? is the original background still used at all or should there be a blending mode change in there too?...Gazraa

Answer:
You duplicate the background layer for a) the chance to play around with opacity- just in case the effect is too strong and b) you should never do anything on the original background- as it is destructive (call me nitpicking- but it's just that I always first duplicate the background.

No you don't change the blending mode- you can flatten it once you are happy.
Stef.

You duplicate the background layer for a) the chance to play around with opacity- just in case the effect is too strong and b) you should never do anything on the original background- as it is destructive (call me nitpicking- but it's just that I always first duplicate the background.

No you don't change the blending mode- you can flatten it once you are happy.
Stef.

colour correction- the right settings for levels and curves

Something that just crossed my mind: a lot of people seem to use not exactly the "best" settings when using the white/grey/ or black eyedropper tool in levels or curves. Here is what you should do:

open any image > open curves or levels (doesn't matter the settings will be automatically saved for both) > double click the black colour picker (this opens the settings dialogue box: enter the following values for the R, G, and B fields: 10 in each > O.K. > do the same with the white colour picker but now enter: 245 in all three fields > O.K. and finally do the same with the grey colour picker tool- this time entering 133 in all three fields (this sets the neutral grey) > O.K. > click once more O.K.- it will ask you whether you want to save these settings > yes

By using 10 for the dark colour picker we make sure that we get dark shadows while still maintaining some detail- the same for white and 133 is the neutral grey.

Try it- it makes you life easier...
Stef.

HI stef
Thats a great way of converting to B/W.Been using that way for a while now after seeing the great late Barry Thomas using it some time ago. Keep up your great tips.

   Regards Steve

converting to black and white

We have done a couple of b/w conversions so far but this one is one of my favourite ones!

1. open you colour image
2. set your foreground colour to black by pressing D on your keyboard
3. layer > new adjustment layer > gradient map > now you have two options: either you just click O.K. and voila you are done or you might want to adjust the midtones/ contrast:
4. click once directly in the b/w gradient- this opens the gradient dialogue box: click under the gradient somewhere in the middle of the whole line > this will turn your image much darker BUT: double click the colour stop you have just put in the middle under your gradient and this will open another dialogue box > you will see in the big colour square on the left hand side bottom a little white circle > click on that circle and move it a bit up (straight line) > release the mouse from time to time to check your results > moving the circle up and down will adjust your midtones > click O.K. > O.K. again > O.K. again once you are happy. If you would like to colour your image at the same time just move you little circle a little bit to the right and see what happens.

Variation:
a) Last but not least you can lower the opacity of that gradient map layer and you will have a "slightly" coloured image.
b) Click on your original background layer> new > adjustment layer (this will create an adjustment layer between the gradient map layer and the background layer) > hue saturation > play around with the saturation slider until you are even happier!

This is a very easy and effective way to convert your images to black and white! Now you might wonder why we have now SO many different ways of converting colour to black and white? Guess it all boils down to taste. Sometimes when I am not completely happy with my conversion I duplicate the original image a couple of times and try all methods- even worse- if I am still not happy I might take two different conversions copy/ paste one of them into the other and start masking/ erasing part of one to let the other one "shine" through.

Some of you might have figured out by now- I just love b/w!

Hope this is useful for some of you and this is not only CS3!

Happy photoshopping
Stef.

Frankly- I go what I am mostly asked for by students- and bw is apparently somewhat important. No worries- there is just another two or three- but I will not deal with them as I don't like them. So from now on different stuff.
Stef.

Quick fix for under/- overexposed images:

This can work wonders...

1. duplicate your background layer in Photoshop
2. underexposed images: set the blending mode of this duplicate layer to screen to lighten the image
    overexposed images: set the blending mode of the new layer to multiply to darken the image
3. if step 2 is not enough just repeat it and lower the opacity of that layer until it looks good.

Note: if you only want a partial effect either erase part of the layer or play around with layer masks!

Happy photoshopping!
Stef.