The format is used on the R-Car VSP1 video queues that carry 2-D histogram statistics data. Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>tirimbino
Niklas Söderlund
9 years ago
committed by
Mauro Carvalho Chehab
parent
f2421521de
commit
5deb1c04c9
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.. -*- coding: utf-8; mode: rst -*- |
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.. _v4l2-meta-fmt-vsp1-hgt: |
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******************************* |
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V4L2_META_FMT_VSP1_HGT ('VSPT') |
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******************************* |
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Renesas R-Car VSP1 2-D Histogram Data |
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Description |
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=========== |
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This format describes histogram data generated by the Renesas R-Car VSP1 |
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2-D Histogram (HGT) engine. |
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The VSP1 HGT is a histogram computation engine that operates on HSV |
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data. It operates on a possibly cropped and subsampled input image and |
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computes the sum, maximum and minimum of the S component as well as a |
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weighted frequency histogram based on the H and S components. |
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The histogram is a matrix of 6 Hue and 32 Saturation buckets, 192 in |
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total. Each HSV value is added to one or more buckets with a weight |
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between 1 and 16 depending on the Hue areas configuration. Finding the |
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corresponding buckets is done by inspecting the H and S value independently. |
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The Saturation position **n** (0 - 31) of the bucket in the matrix is |
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found by the expression: |
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n = S / 8 |
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The Hue position **m** (0 - 5) of the bucket in the matrix depends on |
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how the HGT Hue areas are configured. There are 6 user configurable Hue |
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Areas which can be configured to cover overlapping Hue values: |
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:: |
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Area 0 Area 1 Area 2 Area 3 Area 4 Area 5 |
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________ ________ ________ ________ ________ ________ |
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\ /| |\ /| |\ /| |\ /| |\ /| |\ /| |\ / |
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\ / | | \ / | | \ / | | \ / | | \ / | | \ / | | \ / |
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X | | X | | X | | X | | X | | X | | X |
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/ \ | | / \ | | / \ | | / \ | | / \ | | / \ | | / \ |
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/ \| |/ \| |/ \| |/ \| |/ \| |/ \| |/ \ |
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5U 0L 0U 1L 1U 2L 2U 3L 3U 4L 4U 5L 5U 0L |
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<0..............................Hue Value............................255> |
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When two consecutive areas don't overlap (n+1L is equal to nU) the boundary |
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value is considered as part of the lower area. |
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Pixels with a hue value included in the centre of an area (between nL and nU |
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included) are attributed to that single area and given a weight of 16. Pixels |
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with a hue value included in the overlapping region between two areas (between |
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n+1L and nU excluded) are attributed to both areas and given a weight for each |
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of these areas proportional to their position along the diagonal lines |
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(rounded down). |
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The Hue area setup must match one of the following constrains: |
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:: |
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0L <= 0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U |
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:: |
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0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U <= 0L |
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**Byte Order.** |
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All data is stored in memory in little endian format. Each cell in the tables |
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contains one byte. |
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.. flat-table:: VSP1 HGT Data - (776 bytes) |
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:header-rows: 2 |
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:stub-columns: 0 |
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* - Offset |
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- :cspan:`4` Memory |
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* - |
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- [31:24] |
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- [23:16] |
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- [15:8] |
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- [7:0] |
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* - 0 |
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- - |
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- S max [7:0] |
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- - |
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- S min [7:0] |
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* - 4 |
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- :cspan:`4` S sum [31:0] |
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* - 8 |
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- :cspan:`4` Histogram bucket (m=0, n=0) [31:0] |
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* - 12 |
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- :cspan:`4` Histogram bucket (m=0, n=1) [31:0] |
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* - |
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- :cspan:`4` ... |
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* - 132 |
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- :cspan:`4` Histogram bucket (m=0, n=31) [31:0] |
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* - 136 |
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- :cspan:`4` Histogram bucket (m=1, n=0) [31:0] |
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* - |
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- :cspan:`4` ... |
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* - 264 |
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- :cspan:`4` Histogram bucket (m=2, n=0) [31:0] |
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* - |
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- :cspan:`4` ... |
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* - 392 |
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- :cspan:`4` Histogram bucket (m=3, n=0) [31:0] |
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* - |
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- :cspan:`4` ... |
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* - 520 |
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- :cspan:`4` Histogram bucket (m=4, n=0) [31:0] |
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* - |
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- :cspan:`4` ... |
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* - 648 |
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- :cspan:`4` Histogram bucket (m=5, n=0) [31:0] |
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* - |
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- :cspan:`4` ... |
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* - 772 |
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- :cspan:`4` Histogram bucket (m=5, n=31) [31:0] |
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