DC_READ_8_BIT Function

Reads an 8-bit image file.


0	Indicates an error, such as an invalid filename.
0	Indicates a successful read.

Keywords

XSize

The width (size in the x direction) of imgarr. XSize is computed and output if imgarr is not explicitly dimensioned. XSize is returned as an integer.

YSize The height (size in the y direction) of imgarr. YSize is computed and output if imgarr is not explicitly dimensioned. YSize is returned as an integer.

Discussion

DC_READ_8_BIT handles many steps that you have to do yourself when using other PV-WAVE functions and procedures. These steps include: 1) opening the file, 2) assigning it a logical unit number (LUN), and 3) closing the file when you are done reading the data.

If the dimensions of the byte array imgarr are not known, DC_READ_8_BIT makes a "best guess" about the width and height of the image. It guesses by checking the number of bytes in the file and comparing that number to the number of bytes associated with the following common image sizes:


Image Width	Image Height
640	480
640	512
128	128
256	256
512	512
1024	1024

If no match is found, DC_READ_8_BIT resorts to assuming that the image is square, and returns XSize and YSize as the square root of the number of bytes in the file.

NOTE: You do not need to explicitly dimension imgarr, but if your image data is not one of the standard sizes shown above, you will get more predictable results if you dimension imgarr yourself.

Example

If still_life.img is a 640-by-480 image file, the function call:

status = DC_READ_8_BIT('still_life.img',  $
    s_life, XSize=xdim, YSize=ydim)

reads the binary data in the file still_life.img and transfers it to a variable named s_life. It also returns xdim=640 and ydim=480, since these keywords were provided in the function call.

On the other hand, if still_life.img is a 200-by-350 image file, the values returned are xdim=264 and ydim=264. The keyword results xdim and ydim are computed by taking the square root of the number of bytes in the file. This conversion is done because 200-by-350 is not a "common" image size for which DC_READ_8_BIT checks.

DC_READ_8_BIT Function

Usage

Input Parameters

Output Parameters

Returned Value

Keywords

Discussion

Example

See Also