Browse Prior Art Database

Method for Displaying Large Images Using a Hardware Video Assist Capability

IP.com Disclosure Number: IPCOM000117475D
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Flurry, GA: AUTHOR

Abstract

A method is disclosed which allows the display of large images with a hardware image scaling engine. The method uses a multi-pass approach in both the vertical and horizontal dimensions to circumvent image size restrictions imposed by the hardware.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Method for Displaying Large Images Using a Hardware Video Assist
Capability

      A method is disclosed which allows the display of large images
with a hardware image scaling engine.  The method uses a multi-pass
approach in both the vertical and horizontal dimensions to circumvent
image size restrictions imposed by the hardware.

      The disclosed embodiment of the method is a device driver for
the image scaling engine.  To circumvent the engine height
restriction (general imposed by memory limitations), the method
depends on the concept of image "bands."  With bands, the user
wishing to display an image that is too high is responsible for
breaking the large image up into multiple horizontally oriented
bands, each of which can be handled  by the hardware.  The user can
then call the device driver to display each band, much in the same
manner, but not exactly the same, as if each  band were an
independent image.

      To circumvent the engine width restriction, the device driver
divides the image into a number of "equal" sections as close as
possible to the maximum width the engine can accept; then it uses the
engine in multiple passes to process each section serially.

      Displaying a large image using the device driver is a two step
process.  The user must first call the "image prepare" to set up the
device driver for displaying image bands, and then call "image
display" to display each band of the image.  The parameters for
"image prepare" include the actual image height, an indication to use
bands, and also the maximum height of an image band (for memory
allocation in the device driver).  This information is saved in an
"image structure" for use by "image display."  The parameters for
"image display" include an indication that the user wants to display
an image band, the starting point (in s...