texture import settings

sRGB (Color Texture)

• instructs the GPU to convert data from sRGB color (gamma) space to linear color space when it samples the texture in a shader
  • gamma space: 更接近人眼明暗感知, eg:伽马校正
  • linear space: 线性颜色空间，更精确

Alpha Source

• Specify how the alpha channel of the Texture is generated
  • Input Texture Alpha: This uses the alpha from the input Texture if a Texture is provided.

Alpha is Transparency

• Enable this property to dilate(膨胀) the color and avoid filtering artifacts on the edges if the alpha channel you specify is Transparency.
  • filtering artifacts: 过滤伪影是指在数字信号处理中，由于采样、量化等原因，信号中出现的不真实的频率成分，需要通过滤波器进行去除。

Non Power of 2(非2的幂)

• defines a scaling behavior at import time
  • Ideally, Texture dimension sizes should be powers of two on each side (that is, 2, 4 ... 512, 1024 pixels (px), and so on)
  • Options:
    • To nearest: Scale the Texture to the nearest power-of-two dimension size at import time. For example, a 257x511 px Texture is scaled to 256x512 px.

Read/Write Enabled

• 可读纹理，便于脚本Texture2D.SetPixels/GetPixels方法获取
  • doubles the amount of memory

Streaming Mip Maps

• 指的是动态生成和加载mip贴图级别的技术
• mipmaps:trades a small amount of CPU resources to save a potentially large amount of GPU memory
  • 是一组不同分辨率的纹理,包含从高到低一系列缩小版本的同一纹理。
  • 其目的是根据视角和表面细节自动选择合适分辨率的纹理加速渲染
  • mip是多级渐进纹理(multum in parvo)的缩写,意为“小空间内的许多信息”。

Generate Mip Maps

• 生成mip贴图

ASTC 4x4

• 纹理压缩格式：“自适应表面压缩纹理”(Adaptive Scalable Texture Compression)
• ASTC 4x4指的是该格式使用4x4个像素为基本压缩单位,每个块包含16个像素。它提供RGB和RGBA两种纹理压缩格式,RGBA格式还具有alpha通道