https://daichao1997.github.io/tags/%E5%9B%BE%E5%BD%A2/ Recent content in 图形 on Dai Chao Hugo zh-cn Wed, 05 Dec 2018 01:48:01 +0800 https://daichao1997.github.io/posts/tech/image_basics/ Wed, 05 Dec 2018 01:48:01 +0800 https://daichao1997.github.io/posts/tech/image_basics/ <h2 id="color">Color</h2> <ul> <li>Hue: pure color, presented by a circle</li> <li>Saturation: purity of color, how far it is from pure white, which is every color combined</li> <li>Brightness: subjective perception, how far it is from grey</li> <li>Luminance: objective, cd/m2</li> <li>Contrast:</li> <li>Sharpness:</li> </ul> <h2 id="noise">Noise</h2> <p>Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise.</p> <ul> <li>Gaussian noise</li> <li>Salt-and-pepper noise</li> <li>Shot noise</li> <li>Quantization noise</li> <li>Film grain</li> <li>Anisotropic noise</li> <li>Periodic noise</li> </ul> <h2 id="photography">Photography</h2> <h3 id="backlight">Backlight</h3> <p>The process of illuminating the subject from the back. The lighting instrument and the viewer face each other, with the subject in between, creating a <strong>glowing</strong> effect on the edges of subject, which helps to seperate the subject and the background. In photography, a back light (often the sun) that is about sixteen times more intense than the <strong>key light</strong> produces a <strong>silhouette</strong>.</p>