Obtaining White Balance in Photoshop
- Open photograph in PS.
- Make a new empty layer and fill with mid grey (Shift + Backspace).
- Set Blend to Difference.
- Make a new layer and set to Threshold.
- Move the histogram slider to the left. Image now becomes all white. Drag the slider to the right until patches of black show. (approx. 20%).
- Open the eyedropper (“I”) and zoom to a dark area by holding Z
- Shift click on the dark area to place a marker.
- Ctr O to fit screen. Hide all layers and select the bottom layer.
- Add a curves adjustment layer. Choose the grey dropper and click on the marked spot.
- This will set the mid grey for the picture.
- Remove the marker. (V)
- ** You might also wish to adjust the white and black points for a total colour balance.
- Make another Threshold layer.
- Move the slider to the right for white and to the left for black,
- Use the eyedropper tool to place a marker (Shift + eyedropper) for both white and black.
- Re-open the curves layer and with the “black” eyedropper (from curves)
- click on the black point.
- With the “white” eyedropper, click on the white point.
This protocol will set the correct colour balance.
You may not want to use all three (Black/White/grey) points.
Feel free to experiment.
(Ctr+Shift A to return to camera raw or return to Lightroom)