The next step is to remove the unnecessary blurred layer with the original colors, extract the copy of the original picture created beforehand (a sharp copy) and add to its sharp channels L, a, b the correspondent blurred just received differences. The channels state before and after combination is shown at pic 13 and 14; and on the 15 pic – the result for one of the colored channels (b). Don’t get confused that everything is vice versa at the screenshot of the dialog box: Subtract instead of Add, Invert mark,  and offset= + 127instead of -127. It’s just Photoshop 8.0 fails if the offset is less than 0 at 16 bit mode… By the way, you could also use blend mode - Linear Light but with Opacity = 50 %.
 

13

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15

We are almost done. Let’s compare the results. During each using of Replace Color I have written down all its characteristics and repeated the procedure with 0 blurring (it’s an equivalent to the case when the tool is used directly to the exact original picture) without any complicated moves in Lab and out. The direct using of Replace Color has lead to tragic results with the greenery, girl’s face and especially under the boy’s eye. And the using of blurred differences applied to the exact original picture provided the natural effect. Compare the pictures 16-18 where the original picture, direct using of Replace Color and the method of blurred differences are shown.

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18

Have a look at the picture where I have additionally darkened the sky and made it more intense and played with the sand a bit (pic 20, original is pic 19).

Also I have tried to change the dark-lilac shirt of the gentleman with a bright-green in the same method. I just wanted to know what would happen. But everything has its limits and the spirit of Photoshop has kept me softly from doing it…

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20

Of course no one has cancelled the correction efficiency of different areas of the image through the blurred masks. Moreover, the most accurate results, for more time though, can be received in this way. And there is something to be improved here. For example to make the convenient tool Color Range react only for color but not for the brightness. One can refuse from it and create more harmonic mask by using some manipulations at Lab with the selected color and the blend mode – Difference (although you can not make some additions to the colors then). Besides, the independent masks for the colors and brightness come easily and naturally, which can be combined then as you wish.

Dynamic management of layer-masks

It is possible in Photoshop to manage dynamically the layer-masks and mix them to some degree. For example we have created two its components (bright one and colored) and want to use them without mixing physically. Above the Adjustment Layer which performs the required correction but without mask we place the two layers (unchanged Curves for instance) with the inverted masks of both types and make the Knockout Shallow mode to the layers. The white spots of the masks layers cancel the actions of the corrected layer and its actions are summarized. By duplicating the layers you can narrow the effective mask in this or that component dynamically.