visionhdl.PixelsToFrame
Convert pixel stream to frame-based video
Description
visionhdl.PixelsToFrame converts a color or
grayscale pixel stream and control structures into frame-based video. The control
structure indicates 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 specifying custom
dimensions. See Streaming Pixel Interface for details
of the pixel stream format.
Use this object to convert the output of a function targeted for HDL code generation back to frames. This object does not support HDL code generation.
If your design converts frames to a pixel stream and later converts the stream back to
frames, specify the same video format for the FrameToPixels object and the PixelsToFrame object.
Note
Starting in R2016b, instead of using the step
method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For
example, y = step(obj,x) and y = obj(x)
perform equivalent operations.
Construction
P2F = visionhdl.PixelsToFrameP2F, that converts a 1080p pixel stream, with
standard padding, to a grayscale 1080×1920 frame.
P2F = visionhdl.PixelsToFrame(Name,Value)P2F, with additional options specified by one or
more Name,Value pair arguments. Name is a property name and
Value is the corresponding value. Name must
appear inside single quotes (''). You can specify several name-value
pair arguments in any order as Name1,Value1,...,NameN,ValueN.
Properties not specified retain their default values.
Properties
|
Components of each pixel, specified as 1, 3, or 4. Set to 1 for grayscale
video. Set to 3 for color video, for example, {R,G,B} or {Y,Cb,Cr}. Set to 4
to use color with an alpha channel for transparency. The
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Number of pixels transferred on the streaming interface for each cycle,
specified as Note You can simulate System objects with a multipixel streaming interface, but they are not supported for HDL code generation. Use the equivalent blocks to generate HDL code for multipixel algorithms. | ||||||||||||||||||||||||||||||||||||||||||
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Dimensions of the active region of a video frame. To select a predefined
format, specify the
|
Methods
| step | Convert pixel stream to image frame |
| Common to All System Objects | |
|---|---|
release | Allow System object property value changes |
Examples
Convert Between Full-Frame and Pixel-Streaming Data
This example converts a custom-size grayscale image to a pixel stream. It uses the visionhdl.LookupTable object to obtain the negative image. Then it converts the pixel-stream back to a full-frame image.
Load the source image from a file. Select a portion of the image matching the desired test size.
frmOrig = imread('rice.png'); frmActivePixels = 64; frmActiveLines = 48; frmInput = frmOrig(1:frmActiveLines,1:frmActivePixels); figure imshow(frmInput,'InitialMagnification',300) title 'Input Image'
Create a serializer object and specify size of inactive pixel regions.
frm2pix = visionhdl.FrameToPixels(... 'NumComponents',1,... 'VideoFormat','custom',... 'ActivePixelsPerLine',frmActivePixels,... 'ActiveVideoLines',frmActiveLines,... 'TotalPixelsPerLine',frmActivePixels+10,... 'TotalVideoLines',frmActiveLines+10,... 'StartingActiveLine',6,... 'FrontPorch',5);
Create a lookup table (LUT) object to generate the negative of the input image.
tabledata = linspace(255,0,256); inverter = visionhdl.LookupTable(tabledata);
Serialize the test image by calling the serializer object. pixIn is a vector of intensity values. ctrlIn is a vector of control signal structures.
Note: This object syntax runs only in R2016b or later. If you are using an earlier release, replace each call of an object with the equivalent step syntax. For example, replace myObject(x) with step(myObject,x).
[pixIn,ctrlIn] = frm2pix(frmInput);
Prepare to process pixels by preallocating output vectors.
[~,~,numPixelsPerFrame] = getparamfromfrm2pix(frm2pix);
pixOut = zeros(numPixelsPerFrame,1,'uint8');
ctrlOut = repmat(pixelcontrolstruct,numPixelsPerFrame,1);For each pixel in the stream, look up the negative of the pixel value.
for p = 1:numPixelsPerFrame [pixOut(p),ctrlOut(p)] = inverter(pixIn(p),ctrlIn(p)); end
Create a deserializer object with a format matching that of the serializer. Convert the pixel stream to an image frame by calling the deserializer object. Display the resulting image.
pix2frm = visionhdl.PixelsToFrame(... 'NumComponents',1,... 'VideoFormat','custom',... 'ActivePixelsPerLine',frmActivePixels,... 'ActiveVideoLines',frmActiveLines); [frmOutput,frmValid] = pix2frm(pixOut,ctrlOut); if frmValid figure imshow(frmOutput,'InitialMagnification',300) title 'Output Image' end
