抖动与有序抖动

发布于 2024-11-09 19:28:06 字数 61 浏览 5 评论 0原文

我了解抖动的工作原理等,但是抖动与有序抖动之间有什么区别?

还有人能给我指出一些好的资源吗?

I understand how dithering works etc, but what is the differance between dithering vs ordered dithering?

Also can anyone point me to some good resources?

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深海少女心 2024-11-16 19:28:06

摘自此处

随机抖动

随机抖动可以称为
数字半色调的“冒泡排序”
算法。这是第一次尝试
(早在 1951 年就有记载)
修正由产生的轮廓
固定阈值,并且它有
传统上被引用为
大多数数字研究的比较
半色调。事实上,这个名字
“有序抖动”(这将是
稍后讨论)被选择为
对比随机抖动。

有序抖动

虽然图案化是重要的一步
走向数字复制
经典半色调,其主要缺点
是空间扩大(和
分辨率相应降低)
的图像。有序抖动
代表着重大改进
数字半色调在这种空间
失真被消除,并且
然后可以在其中渲染图像
原始尺寸

Taken from here:

Random dither

Random dithering could be termed the
"bubblesort" of digital halftoning
algorithms. It was the first attempt
(documented as far back as 1951) to
correct the contouring produced by
fixed thresholding, and it has
traditionally been referenced for
comparison in most studies of digital
halftoning. In fact, the name
"ordered dither" (which will be
discussed later) was chosen to
contrast random dither.

Ordered dither

While patterning was an important step
toward the digital reproduction of the
classic halftone, its main shortcoming
was the spatial enlargement (and
corresponding reduction in resolution)
of the image. Ordered dither
represents a major improvement in
digital halftoning where this spatial
distortion was eliminated and the
image could then be rendered in its
original size

.

放我走吧 2024-11-16 19:28:06

抖动与有序抖动之间的主要区别在于量化误差传播的方式。

  1. 抖动 - 量化误差从当前像素传播(在 Floyd-Steinberg 中)到右侧、底部和右下像素。因此,每个像素量化都会影响相邻像素。结果,抖动使视觉更加平滑(就像用笔画绘图一样)

Dither Floyd-Steinberg

  1. 有序抖动 - 使用指定大小的图案(矩阵)中的量化误差。在处理像素时,从模式中获得相应的阈值并将其应用于像素。图案中阈值分布的类型决定了将产生的视觉效果。

通常,阈值分布均匀,结果图像尽可能平滑。

有序抖动

例如,如果高值阈值集中在图案中心周围,则效果为“半色调”

半色调抖动

总之,值得一提的是,有序抖动非常简单,而且快得多。它早在 90 年代的 Windows 95/98 中就已使用,当时显示器的分辨率为 256 色或 16 位色。

您可以从 此处获取源代码和演示项目

The main difference between dither vs ordered dither is the way of the quantisation error spreading.

  1. Dither - the quantisation error is spread (in Floyd-Steinberg) from the current pixel, to the right, bottom and right-bottom pixels. Thus, every pixel quantisation affects the neighbour pixels. In results, the dithering has more smooth vision (like drawing with strokes)

Dither Floyd-Steinberg

  1. Ordered dither - the quantisation error is used from a pattern (matrix) with specified size. While processing pixels, a corresponding value for threashold is obtained from the pattern and applied to the pixel. The type of thresholds distribution in the pattern, determines the visual effect that will be produced.

Usually, the thresholds are evenly distributed and the result image is as smooth as possible.

Ordered dither

For example, if the high-value thresholds are concentrated around the center of the pattern, the effect is "halftoning"

Halftone dither

In conclusion it is worth to mention that Ordered dither is far simple and much faster. It was used back in the '90s in Windows 95/98 when the monitors' resolution were 256 colors or 16bit colors.

You can get source code and demo project from here

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