Documentation/userspace-api/media/v4l/metafmt-vsp1-hgo.rst

Source file repositories/reference/linux-study-clean/Documentation/userspace-api/media/v4l/metafmt-vsp1-hgo.rst

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Documentation/userspace-api/media/v4l/metafmt-vsp1-hgo.rst
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Support Tooling And Documentation
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Documentation
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L

.. _v4l2-meta-fmt-vsp1-hgo:

*******************************
V4L2_META_FMT_VSP1_HGO ('VSPH')
*******************************

Renesas R-Car VSP1 1-D Histogram Data


Description
===========

This format describes histogram data generated by the Renesas R-Car VSP1 1-D
Histogram (HGO) engine.

The VSP1 HGO is a histogram computation engine that can operate on RGB, YCrCb
or HSV data. It operates on a possibly cropped and subsampled input image and
computes the minimum, maximum and sum of all pixels as well as per-channel
histograms.

The HGO can compute histograms independently per channel, on the maximum of the
three channels (RGB data only) or on the Y channel only (YCbCr only). It can
additionally output the histogram with 64 or 256 bins, resulting in four
possible modes of operation.

- In *64 bins normal mode*, the HGO operates on the three channels independently
  to compute three 64-bins histograms. RGB, YCbCr and HSV image formats are
  supported.
- In *64 bins maximum mode*, the HGO operates on the maximum of the (R, G, B)
  channels to compute a single 64-bins histogram. Only the RGB image format is
  supported.
- In *256 bins normal mode*, the HGO operates on the Y channel to compute a
  single 256-bins histogram. Only the YCbCr image format is supported.
- In *256 bins maximum mode*, the HGO operates on the maximum of the (R, G, B)
  channels to compute a single 256-bins histogram. Only the RGB image format is
  supported.

**Byte Order.**
All data is stored in memory in little endian format. Each cell in the tables
contains one byte.

.. flat-table:: VSP1 HGO Data - 64 Bins, Normal Mode (792 bytes)
    :header-rows:  2
    :stub-columns: 0

    * - Offset
      - :cspan:`4` Memory
    * -
      - [31:24]
      - [23:16]
      - [15:8]
      - [7:0]
    * - 0
      -
      - R/Cr/H max [7:0]
      -
      - R/Cr/H min [7:0]
    * - 4
      -
      - G/Y/S max [7:0]
      -
      - G/Y/S min [7:0]
    * - 8
      -
      - B/Cb/V max [7:0]
      -
      - B/Cb/V min [7:0]

Annotation

Implementation Notes