Take the file to be targeted and add a levels adjustment layer to the top of the stack in the Layers pane click OK without making any changes. This will be used to target the highlights and shadows.
Add a Threshold layer above the Levels layer. Your image will appear in high contrast black and white. Set the threshold to 245 and click ok.
Turn off the threshold layer and observe the image. This targeting method is easy in images that have white values present.
A detailed white value, Zone 7, should have a digital density of 245-249 and a white without detail, Zone 8, should have a density of 250-254.
First… Target the highlights:
- Turn the Threshold layer on, it is set to 245.
- If the image is all black it is too dark, open the levels layer and adjust the Input Levels:high slider downwards until you see some white dots appear in the thresholded image.
- Close the levels layer and turn off the threshold.
- Evaluate the highlight areas that are white in the thresholded version.
- If you think these should be Zone 8 whites with no detail then reset the Threshold layer to 250 and readjust the levels layer.
If the image is too light then you will need to work on the underlying adjustment layers that are making the highlights too light.
I try to avoid having more then a few pixels of value 255 in an image. If you set the Threshold to 255 and see significant areas of white things will need to be done or that area will be blown out in the print.
In an image with sunlight clouds I have the highest highlights on the clouds between 250-254 with a few pixels of 255.
Then… Target the Shadows:
If you are looking for a full range image with nice whites and snappy blacks then you want a low value around 10-20. I find that if you go below 10 you may be killing important shadow details.
- Adjust the Threshold layer to 10 and hit OK.
- If you don’t see any black spots in the white field then your image is flat.
- Open the levels control and adjust the Input Levels:Low slider upwards until black spots appear in the thresholded image.
Turn off the Threshold layer and you are now ready to make a print that will have good exposure and contrast.
By working with the threshold layer to positively identify values in your file you can map them to the proper digital output densities and get a well exposed print on the first try everytime.
This method will often help you to identify the pesty hot spots that are preventing you from getting more light into your image. If one small highlight pops right up and there are other similar values in the image that are not popping then you can make a mask for the one spot that is too hot to hold it back allowing you to make the image overall lighter.
Give it a try, I am sure you will save some time and money on paper and ink.