Sensor Crop

Overview 

Sensor Crop is a new feature for the second and third generation MV cameras (MV2, MV12, MV22, MV52, MV63, MV72) that allows for configuring a fixed zoom and pan without any loss in image quality.

In the above gif, the camera is streaming at 1080p full-frame (4MP sensor downsampled to 1080p). After selecting a crop region and applying, the output from the sensor is cropped to the selected region at full 1080P. This produces a higher quality, zoomed image for the selected region.

Use Case 

• Sensor crop is best utilized on cameras where physical/logistical limitations of the camera installation location relative to the area of interest prevent:

  • viewing a selection of the frame in greater detail

  • removing portions of the perimeter of the frame that are undesirable

• Some examples might include:

  • Identification: viewing persons entering a building entryway in greater detail for better identification

  • Privacy: removing a portion of the frame that observes a private work desk/area

  • Analytics: removing a portion of the frame that observes passersby outside a glass window

Configuration 

To configure Sensor crop:

• navigate to your camera's "Video Settings" page
• click the "Select crop region" button
• move and/or resize the selection pane to the desired crop region
• click "Apply crop region" to apply this setting

After applying sensor crop:

 

It takes a few moments for the settings to change on the camera. Once the crop is applied, all footage will be recorded with this new view.

 

After applying the change, we can see the region within the frame has been correctly cropped. The Sensor crop "Apply crop region" button has been replaced with a representation of the current crop region. A "Reset crop region" button is now presented in the event the region needs to be reset/reconfigured.

 

Note: The High dynamic range and Sensor crop features cannot be enabled at the same time. Enabling one of these features will disable the ability to configure the other.

As explained below, applying sensor crop changes the Field of View of the camera. If Zones is configured for analytics, the zones will need to be adjusted based on your changes  with Sensor Crop

Sensor Crop vs. Optical Zoom vs. Digital Zoom 

Sensor crop is different from optical and digital zooming. To briefly compare:

• Sensor crop

  • Changes applied after optics but before sampling/storing of footage to enlarge a desired region

  • Crops the sensor to a selected region before capturing a frame and downsampling (if required)

  • Requires no moving parts

• Optical Zoom

  • Changes applied to optics to enlarge a desired region

  • Alters the focal length/aperture/etc when capturing footage

  • Requires moving parts

• Digital Zoom
  • Applied after optics and sampling/storing of footage to enlarge a desired region
  • Upsamples the footage in software and may require additional processing for pixel inferences
  • Requires no moving parts

Technical Breakdown 

How It Works

With Sensor Crop, there is no pixelation because the image is never upscaled.

The sensor captures raw video at 4 megapixels (2688x1520). This is then scaled down to 1080p or 720p before saving to local storage.

 

The difference between these frame sizes is illustrated below:

 

Instead of simply scaling the whole frame down to our desired resolution, we can crop the image first. The result is a zoomed image of up to 2.1x (720p) or 1.4x (1080p).

There's no loss of quality because we're not scaling up and inferring the values of pixels. They're all read directly from the sensor.

 

 

The "more information" link reveals a modal which explains how the feature works.