The histogram is a graphical representation of all the Pixel values from the camera. The horizontal axis will always display the bit values from the camera. For instance, a 8-bit camera will show 256 entries. A 10-bit camera will show 1024 entries and a 12-bit camera will show 4096 entries. The vertical axis represents the number of pixels at that hue intensity (for colour cameras), or intensity (for mono cameras).

The histogram will also display the intensity value for Red, Green and Blue channel of a color camera. The Sharpness score and Frame Rate values are also displayed in this panel.

To enable the histogram, click the histogram icon under the preview window:

Focus Score (or Sharpness Score) of an image is a metric of how many ‘crisp’ edges there are in the image. Higher values indicate the presence of more edges. 

Frame Rate is the user set frame rate of the camera. This can be changed on the Controls tab

Actual Frame Rate is the number of frames the camera is actually capturing. This is generally the same as the Frame Rate, but it may be lower if Bandwidth Limit is used to  limit bandwidth from the camera, or if the current exposure value is limiting the camera's frame rate. 

Preview Frame Rate is the frame rate of Pixelink Capture's preview display. This will generally be the same as the Actual Frame Rate, but it may be lower if Hardware or Software Trigger is enabled, and the camera is triggered at a lower rate.

For higher resolution cameras, the preview frame rate may also be lower due to the time required to convert and display a high resolution image. Pixelink Capture displays images in RGB format, so switching to a RGB24 or BGR24 pixel format (available, for some cameras, in release 10.7) may increase the preview frame rate, as this reduces the work required for conversion.