Image Effects

How to Use (30 seconds)

1.Upload your image using the file selector or drag-and-drop interface.
2.Adjust the Blur slider (0-100) to apply Gaussian blur with radius σ proportional to slider value.
3.Adjust the Sharpness slider (0-100) to apply unsharp masking with amount scaling.
4.Preview changes in real-time, then download the processed image in original format.

Technical Logic Behind Image Processing

Gaussian Blur Algorithm

Blur applies a Gaussian convolution kernel to each pixel, averaging neighboring pixels weighted by distance. The formula for a 2D Gaussian function is:

G(x, y) = (1 / (2πσ²)) × e^(-(x² + y²) / (2σ²))

Where σ (sigma) is the standard deviation controlling blur radius. Our tool maps slider values linearly:

Slider 0 → σ = 0 (no blur)
Slider 50 → σ = 5 pixels
Slider 100 → σ = 10 pixels (maximum blur)

Unsharp Masking for Sharpening

Sharpening uses unsharp masking (USM), a technique from analog photography. The process:

Create a blurred copy of the original image (Gaussian blur with σ = 1)
Subtract the blurred version from the original to create an edge mask
Add the scaled mask back to the original image

Mathematical formula:

Sharpened = Original + (Amount × (Original - Blurred))

Amount scales from 0 (no sharpening) to 2.0 (maximum sharpening) based on slider position. Values above 1.5 may introduce haloing artifacts around high-contrast edges.

Understanding Your Results

Optimal Settings by Use Case

Use Case	Blur Setting	Sharpness Setting	Purpose
Portrait Photography	10-20	0-10	Soften skin, reduce blemishes
Product Photography	0	40-60	Emphasize texture and detail
Background Separation	60-100	0	Create bokeh effect, isolate subject
Scanned Documents	0	70-90	Enhance text readability
Privacy/Anonymization	80-100	0	Obscure faces, license plates

Quality Degradation Thresholds

Watch for these warning signs:

Sharpness > 75: Haloing artifacts appear around edges (white/dark outlines)
Blur > 50: Fine details become irrecoverable; avoid if re-editing later
Combined extreme values: Blur + Sharpness both > 60 creates unnatural texture

Professional Techniques

💡 Pro Tip: Selective Sharpening Workflow

Professional photographers never sharpen entire images uniformly. Here's the technique most online tools won't tell you:

Process twice: Export one version with sharpness at 50-60, another at 0
Layer in external editor: Stack both versions in Photoshop/GIMP
Mask strategically: Apply sharpness only to eyes, hair, and key details—leave smooth areas untouched
Result: Natural-looking sharpness without over-processed skin or artifacts

💡 Pro Tip: Blur Radius and Image Resolution

The same slider value produces different visual results based on image resolution. For consistent blur across different images:

1080p images (1920×1080): Use slider values as-is
4K images (3840×2160): Double the slider value to match 1080p appearance
8K images (7680×4320): Quadruple the slider value

This is because σ (sigma) is measured in absolute pixels, not relative to image dimensions. A σ=5 blur on a 4K image appears half as strong as the same σ=5 on a 1080p image.

Technical Specifications

Processing Details

•Color space: RGB processing with per-channel convolution (preserves color accuracy)
•Kernel size: Automatically calculated as 6σ + 1 to ensure 99.7% Gaussian distribution capture
•Edge handling: Reflect padding to avoid dark borders on blur operations
•Bit depth preservation: Maintains original 8-bit or 16-bit depth (no quality loss from processing)
•Performance: Client-side processing using WebGL acceleration (no server upload required)

Supported Formats

Input Formats

• JPEG (.jpg, .jpeg)
• PNG (.png)
• WebP (.webp)
• BMP (.bmp)

Output Formats

• Matches input format
• Original EXIF data preserved
• Max file size: 50MB
• Max resolution: 8192×8192px

Algorithm Comparison

Understanding alternatives helps you choose the right tool for your workflow:

Method	Best For	Limitations
Gaussian Blur (This Tool)	Natural-looking blur, privacy masking, depth-of-field simulation	Uniform blur (no edge preservation)
Box Blur	Fast processing on mobile devices	Less smooth, visible artifacts
Bilateral Filter	Smoothing while preserving edges (portrait skin smoothing)	10-20× slower than Gaussian
Unsharp Mask (This Tool)	General-purpose sharpening, text enhancement	Can amplify noise at high values
High Pass Filter	Extreme detail enhancement, texture emphasis	Requires manual layer blending

Common Mistakes to Avoid

❌ Over-sharpening compressed JPEGs

Sharpening amplifies JPEG compression artifacts (8×8 pixel blocks). If your source image shows blocky patterns, reduce sharpness below 30 or convert to PNG before processing.

❌ Applying blur to remove background objects

Gaussian blur doesn't remove objects—it makes them semi-transparent. For actual background removal, use object detection tools with alpha masking instead.

❌ Sharpening already-sharp images

Images from modern cameras (post-2018) often have in-camera sharpening applied. Adding more creates unnatural crispness. Test at 20-30 first.

Technical References

[1] Gonzalez, R. C., & Woods, R. E. (2018). Digital Image Processing (4th ed.). Pearson. Chapter 3: Image Enhancement in the Spatial Domain, pp. 127-156. (Gaussian blur mathematical foundation)
[2] Polesel, A., Ramponi, G., & Mathews, V. J. (2000). Image enhancement via adaptive unsharp masking. IEEE Transactions on Image Processing, 9(3), 505-510. doi:10.1109/83.826787 (Unsharp masking algorithm standards)

This tool implements industry-standard algorithms as documented in peer-reviewed image processing literature. Processing occurs entirely client-side; no images are uploaded to servers.