This is machine translation

Translated by Microsoft
Mouseover text to see original. Click the button below to return to the English version of the page.

Note: This page has been translated by MathWorks. Click here to see
To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

Frame To Pixels

Convert frame-based video to pixel stream

  • Library:
  • Vision HDL Toolbox / I/O Interfaces

Description

The Frame To Pixels block converts color or grayscale video frames to a pixel stream and control signals. The control signals indicate the validity of each pixel and its location in 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. For details of the pixel stream format, see Streaming Pixel Interface.

This block does not support HDL code generation. However, you can use this block to generate input for a separate subsystem targeted for HDL code generation.

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.

Ports

Input

expand all

Full image frame, specified 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.

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

Output

expand all

Single image pixel in a pixel stream, returned as a scalar or a vector of 1-by-Number of components values. The output data type is the same as the data type of the frame port.

Control signals accompanying pixel stream, returned as a pixelcontrol bus containing five signals. The signals describe the validity of the pixel and the location of the pixel within the frame. See Pixel Control Bus.

Data Types: bus

Parameters

expand all

Number of values used to represent each pixel. Each pixel can have 1, 2, 3, or 4 components. Set this parameter to 1 for grayscale video. Set this parameter to 3 for color video, for example, {R,G,B} or {Y,Cb,Cr}. Set this parameter to 4 to use color with an alpha channel for transparency.

Dimensions of active and inactive regions in a video frame. To select a predefined format, select from the Video format list. The actual frame dimensions are displayed in the Video Format Parameters section. For a custom format, select Custom, and then specify the dimensions as integers. The dimensions are defined in the diagram.

Note

The sample time of your video source must match the total number of pixels in the frame of your Frame To Pixels block. The total number of pixels is Total pixels per line × Total video lines, so set the sample time to this value.

Video FormatActive Pixels Per LineActive Video LinesTotal Pixels Per LineTotal Video LinesStarting Active LineEnding Active LineFront PorchBack Porch
240p320240 40232412404438
480p6404808005253651516 144
480pH7204808585253351216122
576p7205768646254762212132
720p1280720165075025744110260
768p102476813448061077724296
1024p128010241688106642106548360
1080p (default)192010802200112542112188192
1200p160012002160125050124964496
2KCinema204810802750112542112163963
4KUHDTV384021604400225042220188472
8KUHDTV7680432088004500424361881032
CustomUser-
defined
User-
defined
User-
defined
User-
defined
User-
defined
User-
defined
User-
defined
User-
defined

When using a custom format, the values you enter for the active and inactive dimensions of the image must add up to the total frame dimensions. If you specify a format that does not conform to these rules, the block reports an error.

  • For the horizontal direction, Total pixels per line must be greater than or equal to Front porch + Active pixels per line. The block calculates Back porch = Total pixels per lineFront porchActive pixels per line.

  • For the vertical direction, Total video lines must be greater than or equal to Starting active line + Active video lines − 1. The block calculates Ending active line = Starting active line + Active video lines − 1.

When using the Line Memory block, or blocks that use an internal line memory, with a custom video format, further requirements apply:

  • Active pixels per line must be greater than 1.

  • The horizontal blanking interval, or Back porch + Front porch, must meet these guidelines:

    • The total of Back porch + Front porch must be at least 2 times the largest kernel size of the algorithm in the blocks following the Frame To Pixel block. If the kernel size is less than 4, the total porch must be at least 8 pixels.

    • The Back porch must be at least 6 pixels. This parameter is the number of inactive pixels before the first valid pixel in a frame.

Introduced in R2015a