术语表

Alpha Channel

Alpha Channel (Transparency Mask)

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.

Aspect Ratio

Aspect Ratio (Width-to-Height Proportion)

Aspect ratio is the proportional relationship between an image's width and height, expressed as two numbers separated by a colon. Common ratios include 16:9 (widescreen), 4:3 (classic), and 1:1 (square).

AVIF

AVIF（AV1图像文件格式）

基于AV1视频编解码器的下一代图像格式，以卓越的压缩效率提供比JPEG小50%的文件，同时支持HDR、宽色域和透明度。

Chroma Subsampling

Chroma Subsampling (Color Resolution Reduction)

Chroma subsampling reduces the color resolution of an image while preserving full brightness (luminance) detail. Human eyes are less sensitive to color changes than brightness changes, making this an efficient compression technique.

Chromatic Aberration

A lens defect causing color fringing at edges where different wavelengths of light focus at slightly different points.

Color Grading (Image)

Image Color Grading

Adjusting color balance, contrast, and tone curves to achieve a desired mood or visual style in an image.

Compression Artifact

Compression Artifact (Visual Distortion)

Compression artifacts are visible distortions introduced by lossy compression algorithms. Common artifacts include blockiness (JPEG macroblocks), ringing around sharp edges, color banding in gradients, and mosquito noise.

Dithering (Image)

Image Dithering

A technique that simulates additional colors by arranging limited-palette pixels in patterns that blend visually.

Image Histogram

A graphical representation of pixel intensity distribution in an image, used to assess exposure and contrast.

Image Registration

Aligning two or more images of the same scene taken at different times, viewpoints, or by different sensors.

Metadata

Metadata (Image Descriptive Data)

Image metadata is information embedded within an image file that describes its properties, origin, and content. This includes EXIF camera data, IPTC editorial information, XMP descriptive tags, and ICC color profiles.

Resolution

分辨率（像素尺寸）

数字图像中的像素总数，以宽×高表示（例如1920 × 1080）。分辨率决定图像细节水平，影响屏幕显示清晰度和打印质量。

Alpha Compositing

Combining semi-transparent images by blending pixel colors according to their alpha channel values.

Image Pyramid

A multi-scale representation of an image at progressively lower resolutions, used in image analysis and blending.

Rasterization

Rasterization (Vector-to-Pixel Conversion)

Rasterization is the process of converting vector graphics (mathematical shapes) into raster images (pixel grids). This is necessary when displaying SVG, PDF, or font glyphs on pixel-based screens or exporting to bitmap formats.

Color Space

Color Space (Color Model)

A color space is a specific organization of colors that defines the gamut (range) of representable colors. sRGB is the web standard, Adobe RGB covers more greens and cyans for print, and Display P3 serves modern wide-gamut displays.

Lossy Compression

Lossy Compression (Perceptual Data Reduction)

Lossy compression achieves much smaller file sizes by permanently discarding image data that is less perceptible to human vision. JPEG, WebP lossy, and AVIF use this approach to achieve 10:1 to 50:1 compression ratios.

Bit Depth

Bit Depth (Color Depth / Bits Per Pixel)

Bit depth determines the number of possible color values each pixel can represent. Higher bit depths allow more colors and smoother gradients: 8-bit provides 256 values per channel (16.7M colors), while 16-bit provides 65,536.

Vector Graphics

Vector Graphics (Resolution-Independent Graphics)

Vector graphics represent images as mathematical descriptions of geometric shapes, paths, and text rather than pixel grids. They scale to any size without quality loss, making them ideal for logos, icons, and illustrations.

Raster Graphics

光栅图形（位图图像）

一种由单独着色的像素组成的矩形网格构成的数字图像类型，图像质量取决于分辨率（像素数量）和颜色深度（每像素的位数）。

HDR

HDR（高动态范围）

一种捕获或表示比标准图像更宽亮度范围的成像技术，保留从深阴影到明亮高光的细节，而标准图像中这些细节会被裁剪掉。

WebP

WebP（网页图片格式）

Google开发的现代图像格式，提供有损和无损压缩，文件大小比JPEG和PNG显著减小，同时保持相当的视觉质量。

Sprite Sheet

精灵图（图像图集）

将多个较小图像排列在网格中组合成单个图像文件，使浏览器或游戏引擎可以通过使用坐标高效选择单个精灵。

Thumbnail

缩略图（预览图像）

大图像的缩小尺寸版本，作为快速视觉预览，常用于图库和搜索结果，供用户在查看完整图像前浏览。

Crop

裁剪（图像区域选择）

选择并仅保留图像的矩形部分，同时丢弃该区域外所有内容的操作。裁剪改善构图、移除不需要的元素或为特定尺寸准备图像。

Resize

调整大小（图像缩放）

通过放大（增大）或缩小（减小）来改变图像像素尺寸的操作。调整大小对于优化网页图像、创建社交媒体模板和准备打印图像至关重要。

Image Optimization

图像优化（网页性能）

在不造成不可接受的视觉质量损失的情况下将图像文件大小减小到尽可能小的过程。图像优化对于快速加载网站和高效带宽使用至关重要。

Image Interpolation

Image Interpolation (Pixel Resampling)

Image interpolation is the method used to calculate new pixel values when resizing an image. Different algorithms (nearest-neighbor, bilinear, bicubic, Lanczos) trade speed for quality when scaling images up or down.

ICC Profile

ICC Profile (International Color Consortium Profile)

An ICC profile is a standardized data file that characterizes a color device (monitor, printer, scanner) or color space. Embedding ICC profiles in images ensures that colors are reproduced accurately across different devices.

Convolution

Convolution (Image Filter Kernel Operation)

Convolution is the fundamental operation behind image filters like blur, sharpen, and edge detection. A small matrix (kernel) slides across the image, computing weighted sums of neighboring pixels to produce the output.

Canvas

Canvas (Image Working Area)

In image editing, the canvas is the total working area that defines the boundaries of the image. Resizing the canvas adds or removes space around the existing image content without scaling it.

DPI/PPI

DPI/PPI (Dots/Pixels Per Inch)

DPI (dots per inch) and PPI (pixels per inch) measure image resolution density. PPI describes screen display density, while DPI refers to print output resolution. 72 PPI is standard for web, 300 DPI for print.

Gamma

Gamma (Brightness Transfer Function)

Gamma describes the nonlinear relationship between pixel values and displayed brightness. A gamma of 2.2 (the sRGB standard) means that pixel value 128 is not 50% brightness but approximately 21.8%, matching human perception.

Histogram

Histogram (Tonal Distribution Graph)

An image histogram is a graph showing the distribution of pixel brightness values from shadows (left) to highlights (right). Photographers and editors use histograms to evaluate exposure, contrast, and tonal balance.

Noise Reduction (Image)

Image Noise Reduction

Techniques for removing unwanted grain or artifacts from images caused by high ISO or low-light conditions.

Panorama Stitching

Panorama Image Stitching

Combining multiple overlapping photographs into a single wide-angle or 360-degree panoramic image.

Image Segmentation

Partitioning an image into multiple regions or objects, used in computer vision for scene understanding.

Object Detection

A computer vision task that identifies and locates objects within an image using bounding boxes and class labels.

Feature Matching

Image Feature Matching

Finding corresponding keypoints between two images for alignment, stitching, or 3D reconstruction.

Mipmap

Mipmap (Multum In Parvo)

A set of pre-computed, progressively smaller versions of a texture used to improve rendering speed and reduce aliasing.

Texture Atlas

A large image containing many smaller sub-images, used in 3D graphics and games to reduce draw calls.

Morphological Operations

Morphological Image Operations

Image processing operations (erosion, dilation, opening, closing) that modify shapes based on a structuring element.

IPTC

International Press Telecommunications Council Metadata

A metadata standard for news photos including caption, creator, copyright, and keyword information.

Gamut Mapping

Color Gamut Mapping

The process of converting colors from one color space to another while handling out-of-gamut colors gracefully.

Tone Mapping

HDR Tone Mapping

Converting high dynamic range image data to a displayable range while preserving visual detail and contrast.

Vignetting

Image Vignetting

The darkening of image corners relative to the center, caused by lens optics or intentionally applied as a creative effect.

XMP

Extensible Metadata Platform

An Adobe-created XML metadata standard for embedding editing history, keywords, and rights information in files.

Focus Stacking

Combining multiple images shot at different focus distances to produce one image with greater depth of field.