Curves Transformation |
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curves can carry out non linear alterations to many channelsUses are many , but after looking at the tool interface I will show a saturation boost and a contrast curve |
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This is not the same as curves in other programs as you can carry out multiple curve alterations at once with all the information clearly displayed , if you have the real time preview open you can judge the multiple effects before applying the alteration to your image You can even open the histogram process at the same time , select the real time preview and see the changes in real time that the curves alterations are making to the histogram. |
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This is the panel of the tool when opened and a image selected |
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A AND B) Modified curves other than the current being worked on C) Current curve--Active curve D) Cursor on curve point--Drag point with mouse to alter curve E) Edit setting--Edit - select and delete default is edit and most used F) Cursor information G) Channel selector-- Being 1) r-g-b single channels 2) combined rgb 3) Alpha 4) CIE lum 5,6,7 ) CIE abc 8) hue 9) saturation
I) Point position J) Zoom tools K) Display options inc single or multiple curves L) Curve options: The button on the left allows you to temporarily save a curve. The middle button will restore the curve to the saved position. The third button will reverse the curve, and the fourth button is the reset M) Interpolation options: . Akima Subspline-Cubic Spline-Linear suggest leave default ( First ) Also you will notice the side and bottom bars go from dark to light this means dark pixels are controlled at the bottom of the curve and bright pixels at the top, so generally if you lift the curve pixels will be bright ned and if you drop the curve they will be darkened.
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How to use Curves Transformation |
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Below I am going to do a saturation boost |
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Click on image to enlarge
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To carry out a saturation boost with curves I did the following 1) Applied a luminance mask to the main image to protect the background ( note to red colour ) 2) selected S ( saturation ) on the channel selector 3) activated the real time preview on the bottom bar ( Bottom image ) 4) lifted up the curve while holding down the top to stop over saturation on bright pixels 5) when I was happy with the curve I closed down the real time preview and applied the alterations to the image 6) Remove mask ( Button on top bar ) and view my new more colorful image |
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Sometimes when processing your image the contrast can be lost and some of this can be put back in with a contrast curve ,so below is how to do a contrast curve |
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Click on image to enlarge
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To carry out a contrast curve I did 1) select rgb on the channel selector 2) activate real time preview 3) pulled down the dark pixel at the bottom of the curve 4) Lifted the upper bright pixel part of the curve We are only after a shallow curve as the main stretching has already been done and we do not want to add noise
Below is a before and after image , rollover your mouse for comparisons |
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| There are may uses of the curves tools and some people wrote a book on that | |
