XIL Data Types

XIL supports a very general image structure and not all types of XIL images are accelerated using VIS and Creator. The XIL data types supported in the VIS port are:

• 1-, 2-, 3-, and 4-banded unsigned byte images
• 1-, 2-, 3-, and 4-banded signed short images
• Band-aligned child images
• All regions of interest
• XIL_PIXEL_SEQUENTIAL type images

Accelerated Functions

Table 7-1 shows the XIL functions accelerated using VIS. Note that display molecules are defined for one- and three-banded XIL_BYTE images.

Table 7-1

Function	VIS Acceleration 8-bit....16-bit		Molecules Display Other		Comments
xil_absolute		1 - 4 bands
xil_affine	1 - 4 bands		x
xil_add	1 - 4 bands	1 - 4 bands	x
xil_add_constant	1 - 4 bands	1 - 4 bands	x
xil_and	1 - 4 bands	1 - 4 bands	x
xil_and_constant	1 - 4 bands	1 - 4 bands	x
xil_band_combine	1 - 4 bands	1 - 4 bands
xil_blend	1 - 4 bands	1 - 4 bands
xil_cast 8 . 16 16 . 8	1 - 4 bands 1 - 4 bands	1 - 4 bands 1 - 4 bands
xil_copy	1 - 4 bands	1 - 4 bands	x
xil_convolve	1 - 4 bands	1 - 4 bands	x		See Note 1
xil_decompress					See Note 2, 5
xil_get_pixel			x		See Note 4
xil_lookup	1 - 4 bands	1 - 4 bands	x	x	See Note 5
xil_min	1 - 4 bands	1 - 4 bands	x
xil_max	1 - 4 bands	1 - 4 bands	x
xil_multiply	1 - 4 bands	1 - 4 bands	x
xil_multiply_constant	1 - 4 bands	1 - 4 bands	x
xil_not	1 - 4 bands	1 - 4 bands	x
xil_or	1 - 4 bands	1 - 4 bands	x
xil_or_constant	1 - 4 bands	1 - 4 bands	x

Table 7-1 (Continued)

Function	VIS Acceleration 8-bit....16-bit		Molecules Display Other		Comments
xil_rescale	1 - 4 bands		x	x	See Note 3, 5
xil_rotate	1 - 4 bands		x		See Note 6
xil_scale	1 - 4 bands	1 - 4 bands	x	x	See Note 5, 6
xil_set_pixel			x		See Note 4
xil_set_value	1 - 4 bands	1 - 4 bands	x
xil_subtract	1 - 4 bands	1 - 4 bands	x
xil_subtract_const	1 - 4 bands	1 - 4 bands	x
xil_subtract_from_const	1 - 4 bands	1 - 4 bands	x
xil_tablewarp			x		See Note 4
xil_threshold	1 - 4 bands	1 - 4 bands	x	x	See Note 3, 5
xil_transpose	1 - 4 bands	1 - 4 bands	x
xil_xor	1 - 4 bands	1 - 4 bands	x
xil_xor_const	1 - 4 bands	1 - 4 bands	x

Notes to Table 7-1

1. xil_convolve is accelerated for 3 . 3, 5 . 5, and 7 . 7 kernels.

2. xil_decompress is accelerated for the following cases:

• xil_decompress + color_convert (JPEG compressed image or sequence and MPEG1 compressed sequence)
• xil_decompress + color_convert + display (JPEG compressed image or sequence and MPEG1 compressed sequence)
• xil_decompress + color_convert + scale + display (MPEG1 compressed sequence)

This decoder adheres to full-precision 24-bit CCIR 601 YCC to RGB709 color space conversion.

There are a few instances when decompression of streams will not be accelerated:

• Decompression of JPEG or MPEG1 streams that are not one contigous buffer in memory is not accelerated. For example, streams split up using xil_cis_put_bits_ptr might not be accelerated.
• If one frame in a stream is not accelerated for some reason (e.g., the decompressor encountered invalid data in the frame), subsequent frames in the stream will not be accelerated.
• Acceleration is also disabled if one tries to seek backwards or forwards in a stream.

3. xil_rescale + xil_threshold + xil_threshold + display molecule is accelerated using the Creator depth-cueing hardware. However, some restrictions apply as follows:

• The first threshold must have a high value of 255. The low and map values must be equal (any number N between 0 and 255.)
• The second threshold must have a low value of 0. The high and map values must be equal (any number M between 0 and N).
• The parameters for xil_rescale must be chosen such that y values of the line represented must span the range of values between N and M while the x values are within 0 and 255. See Figure 7-1.
• The images must be 1-banded XIL_BYTE images.

Figure 7-1

The following code is an example of a correct call to invoke this molecule:

float scale[1] = 1.5; float offset[1] = -10; float t1_lo[1] = 255; float t1_hi[1] = 240; float t1_map[1] = 240; float t2_lo[1] = 0; float t2_hi[1] = 15; float t2_map[1] = 15; xil_rescale(src,tmp1,scale,offset); xil_threshold(tmp1,tmp2,t1_lo,t1_hi,t1_map); xil_threshold(tmp2,tmp3,t2_lo,t2_hi,t2_map); xil_display(tmp3,display);

However, if the same calling sequence is done with scale[1] = .40, the molecule will not be invoked because the line y = 0.40*x -10 only spans the range y = -10 to y = (255*0.40) - 10 = 92 between x = 0 and x = 255. For the molecule to execute, y must span at least the range y = 15 to y = 240 for x between 0 and 255.

4. xil_get_pixel, xil_set_pixel, and xil_tablewarp are accelerated only as display molecules. For xil_tablewarp, only interpolation = "nearest" is accelerated.

5. All of the following molecules (other than a single xil function + display) are accelerated:

• xil_decompress + xil_colorconvert [+ display] (for JPEG)
• xil_decompress + xil_colorconvert [+ display] (for MPEG1)

· xil_decompress + xil_colorconvert + xil_scale + display
 (for MPEG1)
· xil_threshold + xil_threshold [+ display] + [xil_cast] +
 display

• xil_scale + xil_lookup + display (the accelerated molecules are for 8- or 16-bit bilinear scale followed by 8-to-8 bit or 16-to-8 bit lookup)
• xil_scale + xil_lookup + display (the accelerated molecules are 8 or 16-bit bilenear scale followed by 8-to-8 bit or 16-to-8 bit lookup).

6. There are some restrictions on the acceleration of xil_affine, xil_scale, and xil_rotate: xil_affine and xil_rotate are accelerated only for 1-, 3-, and 4-banded images with "nearest" interpolation, and only for 1- and

3-banded images with "bilinear" and "bicubic" interpolation. The restriction for xil_scale is that in the case of interpolation = "general" the size of the resampling kernels are limited to 8 . 8 for 8-bit images, and 8 . 4 for 16-bit images.