Point Grey Grasshopper - Y16 (16-Bit Mono) Image Acquisition; Asynchronous (External) Trigger Modes

Point Grey Research Grasshopper Technical Reference
Camera Operations and Features
Revised 26-Nov-10
Copyright (c) 2010 Point Grey Research Inc.
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frame rates based on selecting a specific region of interest (ROI) of the image or by configuring
the camera to sub-sample the image using a process known as “pixel binning”.
Related Knowledge Base Articles
ID Title URL
163 What are the differences
between pixel binning and region
of interest custom image modes?
www.ptgrey.com/support/kb/index.asp?a=4&q=163
4.5.9. Y16 (16-bit Mono) Image Acquisition
The Grasshopper can output Y16 (16 bit-per-pixel) mono images. However, the number of bits of
usable data is limited to 12, or 4095 possible values, by the following:
• A 14-bit A/D converter.
• On-camera adjustment of sharpness and gamma; on color models, white balance
adjustment and color processing are also involved.
To obtain 14 bits of usable data, or 65,532 possible values, output images in Raw16 format using
one of the following methods:
• Acquire images in Y16 format, and set the Bayer_Mono_Ctrl field of the
IMAGE_DATA_FORMAT register 0x1048 to 1.
• Acquire images in a Format_7 Raw16 format.
Consult the PGR IEEE-1394 Digital Camera Register Reference for more information.
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To determine the number of bits of useable image data, and resulting
signal-to-noise ratio, that is actually being produced by the A/D
converter, see www.ptgrey.com/support/kb/index.asp?a=4&q=170.
The PGM file format can be used to correctly save 16-bit images. However, there are very few
photo manipulation/display applications that can correctly display true 16-bit images. XV in Linux
and Adobe Photoshop are two possibilities.
4.5.10. Asynchronous (External) Trigger Modes
The Grasshopper provides a number of different asynchronous trigger modes, which allows the
start of exposure (shutter) to be initiated by an external electrical source (hardware trigger) or
camera register write (software trigger). Supported modes include: 0, 1, 3, 14 and 15. These
modes and their operation are described in greater detail in the PGR IEEE-1394 Digital Camera
Register Reference.
4.5.10.1. External Trigger Timing
The time from the external trigger going low to the start of shutter is shown below: