Epiphan VGA2USB Pro - Manual (Page 32)

11. About Epiphan frame grabbing technology The Frame Grabber
Page 32 Epiphan Frame Grabber
How Epiphan Frame Grabbers operate
The Frame Grabber is a hardware device that captures images
(also called frames) from analog VGA signals or digital DVI
streams. Capturing images means reading data from the VGA or
DVI signal and converting this data into a digital image.
The Frame Grabber synchronizes itself with the video source to
capture images at the resolution and color depth output by the
video source or at the maximum color depth and resolution
supported by the Frame Grabber. The Frame Grabber captures
images at its own frame rate up to the maximum frame rate
capacity of the Frame Grabber.
Epiphan Frame Grabbers perform the following functions to
optimize and compress captured image data. The aim is to reduce
the amount of data required for each captured image and
optimize data transmission to the video capture workstation.
These functions include:
• Pre-compression using technology developed by Epiphan to
clean up and optimize the image. Pre-compression reduces the
amount of data required for each image and improves the
performance of the standard compression algorithms also
built into most Epiphan Frame Grabbers. See Pre-compression
of computer-generated images on the Epiphan Web Site for a
description of pre-compression.
• Lossless image compression using industry standard image
compression algorithms.
• Optional on-board cropping of the image.
• Color space conversion.
• USB transfer acceleration.
The result is the Frame Grabber captures a large amount of image
data, converts the image data to RGB format at the maximum
color depth that the Frame Grabber supports at the operating
resolution, compresses and optimizes the data and then transmits
the data to the video capture workstation.
All Epiphan Frame Grabbers use USB 1.1 and USB 2.0 to transfer
captured images to the video capture workstation. USB 2.0 is