What is Alpha Channel?

Alpha Channel — Image Transparency Explained

An alpha channel stores transparency information for each pixel in an image, with values ranging from fully transparent to fully opaque. It is the fourth channel in RGBA color, enabling smooth blending of images over backgrounds.

รายละเอียดทางเทคนิค

Alpha values are typically stored as 8-bit (0-255) or floating point (0.0-1.0) per pixel. Pre-multiplied alpha multiplies color values by opacity for faster compositing, while straight alpha stores them independently.

ตัวอย่าง

```javascript
// Convert RGB to HSL
function rgbToHsl(r, g, b) {
  r /= 255; g /= 255; b /= 255;
  const max = Math.max(r, g, b), min = Math.min(r, g, b);
  const l = (max + min) / 2;
  let h = 0, s = 0;
  if (max !== min) {
    const d = max - min;
    s = l > 0.5 ? d/(2-max-min) : d/(max+min);
  }
  return [h, s, l];
}
```

เครื่องมือที่เกี่ยวข้อง

C Compress Image R Resize Image C Crop Image R Rotate Image F Flip Image C Convert Image W Watermark Image S SVG to PNG I Image to Base64 R Round Corners A Add Border I Image Filters A Adjust Image B Blur Image S Sharpen Image M Make Square G Grayscale Image S Sepia Image P Pixelate Image S Strip Image Metadata

คำศัพท์ที่เกี่ยวข้อง

Metadata Rasterization Resolution DPI Color Space Lossy Compression Lossless Compression EXIF Color Profile Bit Depth Vector Graphics Raster Graphics Chroma Subsampling HDR WebP AVIF Sprite Sheet Thumbnail Crop Resize Image Optimization Image Histogram Noise Reduction (Image) Panorama Stitching Image Segmentation Object Detection Feature Matching Image Interpolation Dithering (Image) Alpha Compositing Image Pyramid Mipmap Texture Atlas Image Registration Morphological Operations IPTC ICC Profile Gamut Mapping Tone Mapping Chromatic Aberration Vignetting XMP Color Grading (Image) Focus Stacking Content-Aware Fill Batch Resize Channel Aspect Ratio Convolution Canvas Compression Artifact DPI/PPI Gamma Histogram