Article

ALTRON image display: zooming, reading pixel values and tools

10 October 2026 rahni

In quality control, an image that looks good on the monitor does not always give the right answer. A white spot on a part may really be saturated, or the viewer may simply be showing it as bright. The ALTRON image display resolves this doubt. With it, you zoom in on any point of an area-scan camera image and read the actual value of that pixel.

Which viewer do you have?

ALTRON has two viewers for area-scan cameras. Each camera's ready-made graph already includes one of them:

Image Frame Viewer: is the simple viewer and is included in the ready-made graph of monochrome area-scan cameras. It shows each frame exactly as it arrives from the camera.
Advanced Image Frame Viewer: is the full viewer and is included in the ready-made graph of color area-scan cameras. Area zoom, point cursors and color picking are available only in this viewer.

If you have a monochrome camera and need the full tools, add the Advanced Image Frame Viewer node to the data path in the graph editor. Each viewer opens a separate tab in the middle of the main window. In the tab title you also see the name of the node that feeds it data.

Zoom and pan

Zoom with the mouse wheel.
Right-click and drag to pan the image.
Double-click to return the view to its original state.
In the full viewer, left-click and drag a box to enlarge that area. This is done by the Zoom on Area Selection option, which is on by default.

In the simple viewer, enable zoom and pan with the Zoom / Pan option. Zooming changes only the view and does not touch the recorded data.

Reading pixel values with a cursor

Suppose you want to monitor the black level in a corner of the image and the brightness in its center at the same time. To do this, place point cursors in the full viewer:

In the Advanced Image Frame Viewer settings, under Point Cursor, turn on Show Context Menu. This option is off by default.
Right-click on the image and choose Add cursor to pixel to place a cursor on that pixel. If you know the exact location, Add cursor at X,Y asks you for the column and row numbers.
You can place up to 30 cursors, named P1, P2 and so on. To remove them, choose Remove last cursor or Remove all cursors in the same menu.

Two settings determine how the values are read:

Update Every (ms): how often, in milliseconds, the values refresh. The default is 250. If you uncheck it, the values stay fixed so you can note them down at leisure.
Neighbouring Size: how many surrounding pixels are averaged around the point. The default is 2, and zero means the pixel itself only. If the image is noisy, use a larger value to steady the reading.

Picking the color of a point on a color camera

To compare a part's color with a reference sample, click the point of interest in the full viewer with the middle mouse button. The viewer panel shows two values: the color of the pixel itself and the average color within a circle with a radius of 50 pixels. Copy both as three numbers, R, G and B, with Copy to Clipboard.

Histogram and line profile

Live Histogram: opens from the View menu and is the quickest way to see whether the image brightness has reached the ceiling.
Image Probe: In the full viewer, hold Shift and left-click and drag to create a line profile. Holding Ctrl and dragging draws a box instead. The Image Probe window, from the View menu, shows the data for that line or box.
Full Camera View: Ctrl+F11 hides the side panels so the image fills the screen.

Three common mistakes

Judging saturation by the color of the image. Instead, look at the cursor value or the histogram.
Setting Neighbouring Size to zero on a noisy image and then worrying about a value that keeps jumping up and down.
Placing the viewer after a gamma or sharpening node and expecting to see the raw sensor value. The viewer shows exactly the data flowing at its connection point. To see the raw value, connect the viewer directly after the camera node.

If you'd like to read more about the theory of pixels, this Wikipedia article (English) is a good start.

ALTRON is provided free of charge with all RasaAndishan area-scan cameras. See the models and their specifications on the area scan cameras page. If you are not sure which camera and which settings are right for your application, get help from this page contact us