Sharpen USM | 555Tools — Online Tools for FPGA & Algorithm Engineers

Image AlgorithmsTool Introduction

Sharpen USM (Unsharp Mask) is the most classic sharpening algorithm: first apply Gaussian blur to keep low frequencies, subtract the blurred image from the original to get the high-frequency detail mask, then add the weighted mask back. The threshold parameter suppresses mask values below the threshold, preventing noise amplification in flat areas. Supports amount (0–300%), radius (σ 0.5–5), and threshold (0–40).

Key Formula / Principle

I_blur = Gaussian(I, σ=radius)
mask = I − I_blur
out = I + (amount/100) × mask  (only when |mask| > threshold)

Data Processed Locally|All computations run in your browser. Images, formulas, state machine definitions, and any other input data are never sent to any server.

Related Tools

Color Matrix· Image Algorithms Demosaic· Image Algorithms Auto White Balance· Image Algorithms Gamma Correction· Image Algorithms Spatial Denoise· Image Algorithms Temporal Noise Reduction (TNR)· Image Algorithms Pixel Binning· Image Algorithms Pipeline· Image Algorithms Color Space Converter· Image Algorithms Histogram Analysis· Image Algorithms 3D LUT Color Grading· Image Algorithms Tone Mapping HDR· Image Algorithms HDR Exposure Fusion· Image Algorithms Tone Curve· Image Algorithms CLAHE Auto Contrast· Image Algorithms Black Level Correction· Image Algorithms Defect Pixel Correction· Image Algorithms Lens Shading Correction· Image Algorithms Canny Edge Detection· Image Algorithms Sobel Edge Detection· Image Algorithms Laplacian Edge Detection· Image Algorithms Prewitt / Roberts Edge Detection· Image Algorithms Harris Corner Detection· Image Algorithms Hough Line Detection· Image Algorithms Mean Blur· Image Algorithms Median Filter· Image Algorithms Noise Injection· Image Algorithms Erosion· Image Algorithms Dilation· Image Algorithms Opening· Image Algorithms Closing· Image Algorithms Crop· Image Algorithms Resize· Image Algorithms Resistor Calculator· Basic Tools Ohm's Law· Basic Tools RC/LC Filter· Basic Tools Number / Encoding Converter· Basic Tools CRC Calculator· Basic Tools State Machine Editor· FPGA Tools Timing Diagram Tool· FPGA Tools FIFO Depth Calculator· FPGA Tools CDC Synchronizer Selector· FPGA Tools SDC Constraint Generator· FPGA Tools Setup/Hold Checker· FPGA Tools Timing Budget Analyzer· FPGA Tools Pipeline Calculator· FPGA Tools AI-Verilog Prompt Workbench· FPGA Tools Verilog Code Template Library· FPGA Tools BOM Manager· BOM Management