14.2 Video processing part 1: introductory exercise

Introduction

The purpose of this lab is to acquaint you with the TI Image Developers Kit (IDK). The IDK contains a floating point C6711 DSP, and other hardware that enables real time video/image processing. In addition to the IDK, the video processing lab bench is equipped with an NTSC camera and a standard color computer monitor.

You will complete an introductory exercise to gain familiarity with the IDK programming environment. In the exercise, you will modify a C skeleton to horizontally flip and invert video input (black and white) from the camera. The output of your video processing algorithm will appear in the top right quadrant of the monitor.

In addition, you will analyze existing C code that implements filtering and edge detection algorithms to gain insight into IDK programming methods. The output of these "canned" algorithms, along with the unprocessed input, appears in the other quadrants of the monitor.

Finally, you will create an auto contrast function. And will also work with a color video feed and create a basic user interface, which uses the input to control some aspect of the display.

An additional goal of this lab is to give you the opportunity to discover tools for developing an original project using the IDK.

Important documentation

The following documentation will certainly prove useful:

• The IDK User's Guide . Section 2 is the most important.
• The IDK Video Device Drivers User's Guide . The sections on timing are not too important, but pay attention to the Display and Capture systems and have a good idea of how they work.
• The IDK Programmer's Guide . Sections 2 and 5 are the ones needed. Section 2 is very, very important in Project Lab 2. It is also useful in understanding “streams” in project lab 1.

Video processing - the basics

The camera on the video processing lab bench generates a video signal in NTSC format. NTSC is a standard for transmitting and displaying video that is used in television. The signal from the camera is connected to the "composite input" on the IDK board (the yellow plug). This is illustrated in Figure 2-1 on page 2-3 of the IDK User's Guide. Notice that the IDK board is actually two boards stacked on top of each other. The bottom board contains the C6711 DSP, where your image processing algorithms will run. The daughterboard is on top, it contains the hardware for interfacing with the camera input and monitor output. For future video processing projects, you may connect a video input other than the camera, such as the output from a DVD player. The output signal from the IDK is in RGB format, so that it may be displayed on a computer monitor.

At this point, a description of the essential terminology of the IDK environment is in order. The video input is first decoded and then sent to the FPGA, which resides on the daughterboard. The FPGA is responsible for video capture and for the filling of the input frame buffer (whose contents we will read). For a detailed description of the FPGA and its functionality, we advise you to read Chapter 2 of the IDK User's Guide.