Line Pitch - Basler acA2040-55 User Manual

Features AW00123409000

7.22 Line Pitch

For information about the availability of the line pitch feature on a specific camera model, see
Table 41 on page 191 and Table 42 on page 192.
The line pitch feature is useful if you want that the data size, related to a line of pixels, will be
perfectly aligned with cache lines. Data alignment can improve performance and is in general
desired for embedded systems.
"Line pitch" designates the number of bytes that relate to all pixel data of a line of pixels, subject to
the current ROI width and the current pixel format.
Generally, the line pitch obtained from an image acquisition (the "original" line pitch) will not include
the right number of bytes for perfect alignment with cache lines of given sizes (typically 32 or 64
bytes). For perfect alignment, the line pitch must be a multiple of a given cache line size. To allow
perfect alignment, the line pitch feature will expand the original line pitch as far as necessary to
produce the "minimum required line pitch". The expansion is accomplished by appending the
minimum required bytes as zeros to the original pixel data (data structure padding).
Example: Assume a camera is set for an ROI width of 352 pixels and for Mono 8 pixel format. Also
assume, that the pixel data from each ROI line must align with a cache line size of 64 bytes.
For each frame and with the above settings, each pixel will deliver one byte and each ROI line will
include 352 bytes of pixel data (the original line pitch; see Figure 115 on page 335). This amount of
data can not be aligned with 64-byte cache lines as 352 can not be divided by 64 without remainder.
Alignment is, however, possible, when the line data are padded with 32 bytes (as zeros) to produce
the minimum required line pitch of 384 bytes.
334 Basler ace USB 3.0