Pixels To Frame

Convert pixel stream to frame-based video

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Libraries:
Vision HDL Toolbox / I/O Interfaces

Description

The Pixels To Frame block converts a color or grayscale pixel stream and control signals to frame-based video. The control signal bus indicates the validity of each pixel and its location within the frame. The pixel stream format can include padding pixels around the active frame. You can configure the frame and padding dimensions by selecting a common video format or by specifying custom dimensions. The pixel input can support single pixel streaming, or multipixel streaming. Multipixel streaming accepts 2, 4, or 8 pixels each clock cycle to support high-rate or high-resolution formats. For details of the pixel stream format, see Streaming Pixel Interface.

This block itself does not support HDL code generation. However, you can use this block to convert the output of a separate subsystem, targeted for HDL code generation, back to frames.

If your model converts frames to a pixel stream and later converts the stream back to frames, specify the same video format for the Frame To Pixels block and the Pixels To Frame block.

Examples

Gamma Correction

Model pixel-streaming gamma correction for hardware designs. The model compares the results from the Vision HDL Toolbox™ Gamma Corrector block with the results generated by the full-frame Gamma block from Computer Vision Toolbox™.

• Open Model

Filter Multipixel Video Streams

Design filters that operate on a multipixel input video stream. Use multipixel streaming to process high-resolution or high-frame-rate video with the same synthesized clock frequency as a single-pixel streaming interface. Multipixel streaming also improves simulation speed and throughput because fewer iterations are required to process each frame, while maintaining the hardware benefits of a streaming interface.

• Open Model

Ports

Input

pixel — Input pixel stream

scalar | vector | matrix

For single pixel streams, specify pixel as a scalar or a vector of 1-by-Number of components values that represent a single pixel. For multipixel streams, specify pixel as a matrix of Number of pixels-by-Number of components pixel intensity values. Number of pixels can be two, four, or eight.Number of components can be from one to four.

Data Types: uint | int | fixed point | Boolean | single | double

ctrl — Control signals associated with pixel stream

pixelcontrol bus

The pixelcontrol bus contains five signals. The signals describe the validity of the pixel and its location in the frame. For more information, see Pixel Control Bus.

For multipixel streaming, each vector of pixel values has one set of control signals. Because the vector has only one valid signal, the pixels in the vector must be either all valid or all invalid. The hStart and vStart signals apply to the pixel with the lowest index in the vector. The hEnd and vEnd signals apply to the pixel with the highest index in the vector.

Data Types: bus

Output

frame — Full image frame

array

Full image frame, returned as an Active pixels per line-by-Active video lines-by-N array. The first two array dimensions are the height and width of the active image specified by the Video format parameter. N is the Number of components used to express a single pixel. The output data type is the same as the data type of the pixel port.

Data Types: uint | int | fixed point | Boolean | single | double

validOut — Indicates when output frame is ready

scalar

This signal is 1 (true) when the block has successfully recompiled an output frame from the input stream.

Data Types: Boolean

Parameters

Number of components — Number of values used to represent each pixel

1 (default) | 2 | 3 | 4

Number of values used to represent each pixel. Each pixel can have from 1 to 4 components.

• For grayscale video, set this parameter to 1.

• For color video, for example, {R,G,B} or {Y,Cb,Cr}, set this parameter to 3.

• For color video with an alpha channel for transparency, set this parameter to 4.

To process multicomponent streams for blocks that do not support multicomponent input, replicate the block for each component. The pixelcontrol bus for all components is identical, so you can connect the ctrl output of the Frame To Pixels block to each replicated block.

Number of pixels — Number of pixels streamed per time step

1 (default) | 2 | 4 | 8

Number of pixels transferred on the streaming interface for each time step, specified as 1, 2, 4, or 8. To enable multipixel streaming and increase throughput for high-resolution or high-frame-rate video, set this parameter to 2, 4 or 8. Multipixel streaming processes more pixels with the same clock frequency as a single-pixel streaming interface.

Video Resolution	Clock Frequency Required for Single-Pixel Streaming at 60 fps	Clock Frequency Required for Multipixel Streaming at 60 fps (4 pixels)
1080p	150 MHz	37.5 MHz
4k UHD	600 MHz	150 MHz
8k UHD	1200 MHz	300 MHz

Video format — Dimensions of active regions in a video frame

1080p (default) | 240p | 480p | 480pH | 576p | 720p | 768p | 1024p | 1200p | 2KCinema | 4KUHDTV | 8KUHDTV | Custom

Dimensions of active regions in a video frame. To select a predefined format, use the Video format pull-down menu. The active frame dimensions are set as shown in the table. For a custom format, select Custom, then specify the active frame dimensions as integers.

Video Format	Active Pixels Per Line	Active Video Lines
240p	320	240
480p	640	480
480pH	720	480
576p	720	576
720p	1280	720
768p	1024	768
1024p	1280	1024
1080p (default)	1920	1080
1200p	1600	1200
2KCinema	2048	1080
4KUHDTV	3840	2160
8KUHDTV	7680	4320
Custom	User- defined	User- defined

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

This block supports C/C++ code generation for Simulink^® Accelerator and Rapid Accelerator modes.

Version History

Introduced in R2015a

R2022a: Two pixels-per-clock streaming

The block now supports multipixel streams that have 2 pixels per clock cycle.

R2020a: Multipixel-multicomponent streaming

The block now supports multipixel-multicomponent streams. The block accepts an input matrix of NumPixels-by-NumComponents pixels. The ctrl port remains scalar, and the control signals in the pixelcontrol bus apply to all pixels in the matrix. The MultiPixel-MultiComponent Video Streaming example shows how to use a multipixel and multicomponent pixel stream to process a high-resolution color image.

R2019b: Multipixel streaming

The block now accepts pixel streams that have 4 or 8 pixels per clock cycle. You can set the Number of pixels parameter to 4 or 8. With this setting, the block expects an input vector of 4 or 8 pixel values on each time step. For an example of how to use this feature, see Filter Multipixel Video Streams.