Generate HDL and HLS Code from a High Dynamic Range Imaging Algorithm

R2026b

This example shows how to generate HDL and HLS code from a MATLAB® function that implements a high dynamic range (HDR) imaging algorithm.

Note

This example requires the Image Processing Toolbox™.

High dynamic range imaging combines multiple exposures of the same scene to produce an image that captures detail in both the brightest and darkest regions. The algorithm in this example takes short-exposure and long-exposure images, applies luminance lookup tables (LUTs) to each image, and merges the results into a single HDR image. Photography, surveillance, and automotive vision systems use this technique where a single exposure cannot capture the full intensity range of a scene.

Examine the MATLAB Design and Test Bench

Set up the MATLAB function and test bench for this example. In the MATLAB Command Window, enter:

mlhdlc_demo_setup("mlhdlc_hdr");
This command opens a temporary working folder with the files required to run this example. The folder includes these files:

  • MATLAB function

  • Test bench

  • Short-exposure and long-exposure input images

  • <model>_runme.m script, which includes the commands to generate HDL and HLS code

The MATLAB function, mlhdlc_hdr, processes one pixel at a time. It accepts luminance and chrominance channel values from both exposures, two constant LUT arrays, and pixel validity and coordinate signals. The function maps each luminance value through its corresponding LUT, sums the two mapped values to produce the HDR luminance, and averages the chrominance channels. It outputs the merged HDR pixel along with the forwarded validity and coordinate signals.

To view the function, enter:

open mlhdlc_hdr.m;

The test bench file, mlhdlc_hdr_tb, verifies the behavior of the MATLAB function by reading short-exposure and long-exposure PNG images, converting them to YIQ (luminance, in-phase, quadrature) color space, streaming each pixel through the design, and reconstructing the HDR output image. To view the test bench, enter:

open mlhdlc_hdr_tb.m;

The example also includes mlhdlc_hdr_short.png and mlhdlc_hdr_long.png, which are the short-exposure and long-exposure input images used by the test bench.

Simulate the Design

To check for run-time errors, simulate the design by running the test bench. In the MATLAB Command Window, enter:

mlhdlc_hdr_tb;

Generate HDL Code

The mlhdlc_hdr_runme script specifies the target files, enables the settings required for this example, and generates HDL code.

The script specifies the MATLAB function and test bench, then creates a fixed-point configuration object by using the coder.config function. It associates the test bench with the configuration object and adds a function approximation for the exp function.

designName = "mlhdlc_hdr";
designTB = "mlhdlc_hdr_tb";
fixptCfg = coder.config("fixpt");
fixptCfg.TestBenchName = designTB;

mathFcnGenCfg = coder.approximation("exp");
mathFcnGenCfg.NumberOfPoints = 1024;
mathFcnGenCfg.InterpolationDegree = 0;
fixptCfg.addApproximation(mathFcnGenCfg);

The script creates an HDL configuration object and associates the test bench.

isCodingForHDL = true;
isCodingForStratusHLS = false;
isCodingForVitisHLS = false;

cfg = coder.config("hdl");
cfg.TestBenchName = designTB;

The script then generates code:

codegen("-float2fixed", "fixptCfg", "-config", "cfg", designName, ...
"-launchreport");

Run the Script

First, modify the mlhdlc_hdr_runme script. The script disables synthesis by default. Set the value for the SynthesizeGeneratedCode property to true:

cfg.SynthesizeGeneratedCode = true;

Update the settings for your synthesis tool:

cfg.SynthesisTool = "Xilinx Vivado";
cfg.SynthesisToolChipFamily = "Artix7";
cfg.SynthesisToolDeviceName = "xa7a100t";
cfg.SynthesisToolPackageName = "csg324";
cfg.SynthesisToolSpeedValue = "-1I";

Then, generate code by running the script:

mlhdlc_hdr_runme

After code generation completes, the report opens. Examine the generated HDL code in the report.

Generate HLS Code

The mlhdlc_hdr_runme script can also generate HLS code. If isCodingForHDL is false, the script configures the HDL configuration object for an HLS code generation workflow:

cfg.Workflow = "High Level Synthesis";
cfg.GenerateHDLTestBench = true;
cfg.SimulateGeneratedCode = true;

The script sets the synthesis tool to AMD® Vitis® HLS:

cfg.SynthesisTool = "Xilinx Vitis HLS";
cfg.SynthesisToolChipFamily = "Artix7";
cfg.SynthesisToolDeviceName = "xa7a100t";
cfg.SynthesisToolPackageName = "csg324";
cfg.SynthesisToolSpeedValue = "-1I";

Run the Script

To generate HLS code instead of HDL code, modify the mlhdlc_hdr_runme script. Set the flags so that the script targets an HLS code generation workflow:

isCodingForHDL = false;
isCodingForStratusHLS = false;
isCodingForVitisHLS = true;

The script disables synthesis by default. Set the value for the SynthesizeGeneratedCode property to true:

cfg.SynthesizeGeneratedCode = true;

Depending on your synthesis tool, set one of these flags to true:

isCodingForStratusHLS = false;
isCodingForVitisHLS = true;

Depending on your synthesis tool, update these synthesis tool settings:

if isCodingForStratusHLS
    cfg.SynthesisTool = "Cadence Stratus HLS";
elseif isCodingForVitisHLS
    cfg.SynthesisTool = "Xilinx Vitis HLS";
    cfg.SynthesisToolChipFamily = "Artix7";
    cfg.SynthesisToolDeviceName = "xa7a100t";
    cfg.SynthesisToolPackageName = "csg324";
    cfg.SynthesisToolSpeedValue = "-1I";
end

Then, generate code by running the script:

mlhdlc_hdr_runme

After code generation completes, the report opens. Examine the generated HLS code in the report.

See Also

Functions

Topics