Photo shop tutorials on Curves, part 5

Curves and colour correction

More here on improving tone and colour with curves; soon this will be second nature.

� Go back to the original of the previous image for this tutorial.

� Select the eyedropper with the I key. In the options bar, there are three choices of sample size. For greatest accuracy, the Point Sample will sample from one pixel when the image is zoomed out to 100%.
At a lower percentage, the sample it takes will be from more than one pixel. It needs to be used with care and here the 3 by 3 Average is the best option.

� The standard curves box has a grid of four squares along each side. Press Alt / Opt and click inside the box area. The grid now has ten divisions on each side. This can be useful for precise positioning of the anchor points and the curve.

� To adjust a particular part of the image, place the cursor over the image. Hold Control / Command and click. An anchor point for that spot is placed on the curve. An exact tonal spot can be selected in this manner.

� Sometimes extra anchor points might be required to prevent any adjustment on other parts of the image. For example, an adjustment might be necessary on the midtones but the highlights are fine.
The anchor points at position 1 will lock the highlights.

� In this case, the improvement needs to be over the whole image. Place the cursor on these anchor points and drag them out of the box to delete it. That was just a practice run.
info palette

� Show the Info palette with F8.

� Place the cursor on your grey area, such as the tarmac on the main central motorway. Hold Shift and click to place these readings in the Info palette.

� Without moving the cursor (Go on, put it back), go Ctrl + Shift + click / Cmd + Shift + click. This action puts the anchor point on each of the channels but not on the composite channel. Now the point you have chosen will have an anchor point on each of the red, green and blue curves

photoshop ideas � All the rest you know. The middle setting is the green at 135 so red and blue are adjusted to that.
Ctrl + 1 / Cmd + 1 selects the Red channel, then enter an Output value of 135.
Ctrl + 3 / Cmd + 3 selects the Blue channel. Set its value to 135 also.

� The keyboard arrows can be used to move the anchor point.
Holding Shift moves it 10 pixels at a time.
Physically moving the point with the cursor is clumsy and is best avoided when accuracy is required.

photoshop tutorial downloads Tip Up to 16 anchor points can be put on the curve at once.
To move from one point to another, use
Ctrl + tab / Cmd + tab.
To reverse the choice, use
Ctrl + Shift + tab / Cmd + Shift + tab.

Tip An anchor point can also be moved up and down the curve with the cursor or with the arrow keys on the keyboard.
To remove an anchor point, drag it out of the curves box completely.

More on Curves

A reasonable scan might look something like this, before any Photoshop curves treatment. Colour is pretty close and contrast is a bit low; much better that than a scan which is too punchy and has already lost detail.
Curves can fix it easily.

adjusting skin color

Getting skin colour accurate can be tricky but if it is not right, the error becomes very noticeable.

funny photoshops

Photoshop In A Day contains all this information and further tips about Curves, including special effects.

Curves 1 2 3 4 5