16 Jun Getting Started with Imager
In this tutorial, you will learn how to build a virtual prototype of a front facing mobile camera and look at the impact of using different lens and sensor combinations. If you don’t have Imager, you can download a free trial here.
When you open Imager, it will simulate the default system using sunlight as the source, the 11223 ISO test chart as the object, an F/2 20mm focal length lens, and a VGA sensor. Let’s start by loading in the On Semi MT9D015 sensor and a mobile lens with a 2.7mm focal length and an F/# of 2.5. To import the sensor and lens, download the following files:
In Imager go to File – Import… – From Another Imager File and select the lens and sensor files you just downloaded. You can import the sensor and then the lens without waiting for the simulation to finish. With each change, the simulation restarts, so that when it is finished it will represent all of the changes that were made. We now have a virtual prototype of a typical HD camera that is used as the front facing camera on a mobile phone.
Let’s change the test chart and make it larger so it fills the full field of view. To do this, go to Object and select the scene icon , and select the ISO 12233 E-SFR Enhanced file and select Apply.
Under Object, enter a value of 3m for the Width. We have now changed the scene and increased it size to that it fills the full field of view.
Now let’s look at what happens when we use a larger sensor. In order the see the impact, let’s turn off lens shading correction. Lens shading correction is an algorithm that gains up the corners of the image to compensate for signal loss at the edge of the field which is common in mobile cameras. To turn off lens shading correction, go to Processing and uncheck the Lens Shading Correction checkbox. You will now see that the corners are darker due to the lens relative illumination fall off and due to a mismatch between the lens chief ray angle and the sensor microlens shifts.
Now let’s insert the AR0330 sensor, which is a 3MP sensor with 2.2 micron pixels.
We insert the new sensor as we did before by going to File – Import… – From Another Imager File. Once the simulation is complete, we see that the lens we have selected does not support a sensor as large as the AR0330. This is evident by the dark corners in the image.
Let’s import a lens that can support a large sensor. A good candidate is a common photographic objective. In this example we will use a 12mm focal length F/3 double gauss lens.
We see that the field of view has decreased due to the longer focal length, and that the new system does a great job of resolving the resolution fans on the test chart.
Even though the components we have imported represent real sensors and lenses, we can still change parameters and see their impact. For example, if we want to increase the field of view, we can change the focal length independently of all of the other parameters. In the image below, we have reduced the focal length from 12mm to 6mm.
You can now experiment with a wide variety of parameters and see their impact, like changing the lighting to living room conditions as I show here.
You now know how to set up and modify a camera system in Imager. If you have additional questions about this tutorial, or questions about how to use Imager for your application, post a question below or email us at firstname.lastname@example.org.