Using the Curvemeister Histogram or Composite window to set the highlight and shadow appearance threshold.

This technique is used most frequently when there is no clear shadow or highlight in the scene.  By using the Curvemeister tools to show highlight and shadow areas on the actual image.  This allows you to see very quickly if you have the brightest highlight or darkest shadow in your images.


Let’s do a brief analysis of the above image and see what things we can improve on.

Overall the image looks flat, it is underexposed and the colors look muted.
We can see some areas we need to be interested in:

1.    There are some specular highlights on the bee. There are also specular highlights on the tips of the spikes in the cone flower.

2.    There are shadows in the image that appear to have detail in them but it is unclear if the detail is even recoverable at this point.

3.    This appears to be a brightly lit colorful image.  The muted greens and oranges can be improved.

This is common approach to many images.  Take a minute to look at the problem areas and start thinking about how you can improve these areas.


To begin the process of thresholding you need to open the Curvemeister tool.  The example below is in the LAB color space with the histogram showing the pixels in the image.

Place the mouse on the light side of the graph and left click, you will see a red dashed line.  You will be moving the entire red line to the right in this case.

Drag the line to the right.

When you start to see the specular highlights in the image you have reached the threshold and should stop.

For the shadow threshold grab the Right edge of the CM graph and move the red line to the left. As you do the shadow parts of the image will begin to turn black. This is the Shadow Threshold.

Notice the changes to the Histogram.  The slope of the line has increased.
<More contrast> and the pixels of the histogram now mostly fall between the red lines.

Below is the image after thresholding.  Notice that it is lacking saturation. This is often a by-product of the thresholding process.

Use the Saturation Slider Tool to increase the overall saturation.
In this example the saturation was increased to 1.50