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diff --git a/Documentation/media/v4l-drivers/ipu3.rst b/Documentation/media/v4l-drivers/ipu3.rst index 804f37300623..c9f780404eee 100644 --- a/Documentation/media/v4l-drivers/ipu3.rst +++ b/Documentation/media/v4l-drivers/ipu3.rst @@ -357,6 +357,153 @@ https://chromium.googlesource.com/chromiumos/platform/arc-camera/+/master/ The source can be located under hal/intel directory. +Overview of IPU3 pipeline +========================= + +IPU3 pipeline has a number of image processing stages, each of which takes a +set of parameters as input. The major stages of pipelines are shown here: + +.. kernel-render:: DOT + :alt: IPU3 ImgU Pipeline + :caption: IPU3 ImgU Pipeline Diagram + + digraph "IPU3 ImgU" { + node [shape=box] + splines="ortho" + rankdir="LR" + + a [label="Raw pixels"] + b [label="Bayer Downscaling"] + c [label="Optical Black Correction"] + d [label="Linearization"] + e [label="Lens Shading Correction"] + f [label="White Balance / Exposure / Focus Apply"] + g [label="Bayer Noise Reduction"] + h [label="ANR"] + i [label="Demosaicing"] + j [label="Color Correction Matrix"] + k [label="Gamma correction"] + l [label="Color Space Conversion"] + m [label="Chroma Down Scaling"] + n [label="Chromatic Noise Reduction"] + o [label="Total Color Correction"] + p [label="XNR3"] + q [label="TNR"] + r [label="DDR"] + + { rank=same; a -> b -> c -> d -> e -> f } + { rank=same; g -> h -> i -> j -> k -> l } + { rank=same; m -> n -> o -> p -> q -> r } + + a -> g -> m [style=invis, weight=10] + + f -> g + l -> m + } + +The table below presents a description of the above algorithms. + +======================== ======================================================= +Name Description +======================== ======================================================= +Optical Black Correction Optical Black Correction block subtracts a pre-defined + value from the respective pixel values to obtain better + image quality. + Defined in :c:type:`ipu3_uapi_obgrid_param`. +Linearization This algo block uses linearization parameters to + address non-linearity sensor effects. The Lookup table + table is defined in + :c:type:`ipu3_uapi_isp_lin_vmem_params`. +SHD Lens shading correction is used to correct spatial + non-uniformity of the pixel response due to optical + lens shading. This is done by applying a different gain + for each pixel. The gain, black level etc are + configured in :c:type:`ipu3_uapi_shd_config_static`. +BNR Bayer noise reduction block removes image noise by + applying a bilateral filter. + See :c:type:`ipu3_uapi_bnr_static_config` for details. +ANR Advanced Noise Reduction is a block based algorithm + that performs noise reduction in the Bayer domain. The + convolution matrix etc can be found in + :c:type:`ipu3_uapi_anr_config`. +DM Demosaicing converts raw sensor data in Bayer format + into RGB (Red, Green, Blue) presentation. Then add + outputs of estimation of Y channel for following stream + processing by Firmware. The struct is defined as + :c:type:`ipu3_uapi_dm_config`. +Color Correction Color Correction algo transforms sensor specific color + space to the standard "sRGB" color space. This is done + by applying 3x3 matrix defined in + :c:type:`ipu3_uapi_ccm_mat_config`. +Gamma correction Gamma correction :c:type:`ipu3_uapi_gamma_config` is a + basic non-linear tone mapping correction that is + applied per pixel for each pixel component. +CSC Color space conversion transforms each pixel from the + RGB primary presentation to YUV (Y: brightness, + UV: Luminance) presentation. This is done by applying + a 3x3 matrix defined in + :c:type:`ipu3_uapi_csc_mat_config` +CDS Chroma down sampling + After the CSC is performed, the Chroma Down Sampling + is applied for a UV plane down sampling by a factor + of 2 in each direction for YUV 4:2:0 using a 4x2 + configurable filter :c:type:`ipu3_uapi_cds_params`. +CHNR Chroma noise reduction + This block processes only the chrominance pixels and + performs noise reduction by cleaning the high + frequency noise. + See struct :c:type:`ipu3_uapi_yuvp1_chnr_config`. +TCC Total color correction as defined in struct + :c:type:`ipu3_uapi_yuvp2_tcc_static_config`. +XNR3 eXtreme Noise Reduction V3 is the third revision of + noise reduction algorithm used to improve image + quality. This removes the low frequency noise in the + captured image. Two related structs are being defined, + :c:type:`ipu3_uapi_isp_xnr3_params` for ISP data memory + and :c:type:`ipu3_uapi_isp_xnr3_vmem_params` for vector + memory. +TNR Temporal Noise Reduction block compares successive + frames in time to remove anomalies / noise in pixel + values. :c:type:`ipu3_uapi_isp_tnr3_vmem_params` and + :c:type:`ipu3_uapi_isp_tnr3_params` are defined for ISP + vector and data memory respectively. +======================== ======================================================= + +Other often encountered acronyms not listed in above table: + + ACC + Accelerator cluster + AWB_FR + Auto white balance filter response statistics + BDS + Bayer downscaler parameters + CCM + Color correction matrix coefficients + IEFd + Image enhancement filter directed + Obgrid + Optical black level compensation + OSYS + Output system configuration + ROI + Region of interest + YDS + Y down sampling + YTM + Y-tone mapping + +A few stages of the pipeline will be executed by firmware running on the ISP +processor, while many others will use a set of fixed hardware blocks also +called accelerator cluster (ACC) to crunch pixel data and produce statistics. + +ACC parameters of individual algorithms, as defined by +:c:type:`ipu3_uapi_acc_param`, can be chosen to be applied by the user +space through struct :c:type:`ipu3_uapi_flags` embedded in +:c:type:`ipu3_uapi_params` structure. For parameters that are configured as +not enabled by the user space, the corresponding structs are ignored by the +driver, in which case the existing configuration of the algorithm will be +preserved. + References ========== |