公开(公告)号：US20040257619A1

公开(公告)日：2004-12-23

申请号：US10462966

申请日：2003-06-17

Applicant: Xerox Corporation

Inventor： Robert P. Loce ,  Martin S. Maltz ,  Jay S. Grzenda

IPC: H04N001/52 ,  G06T007/00

CPC classification number: H04N1/40075

Abstract: What is disclosed is an image path that advantageously uses halftone classification to select appropriate mappings in gray-scale management and color management operations. The tags generated in the scanner help identify different classes of halftones. One is selected from several pixel-value mappings to provide proper compensation. That is, the one-dimensional and multi-dimensional pixel-value mappings within the color management module are selected based on halftone classification tags from the scanner. The tagging is either one bit that indicates nullLow Frequency Halftonenull and nullNot LFHTnull, or, more preferably, the tag is multi-bit indicating a frequency bin that contains the frequency of the input halftone. Additionally, the multi-bit tag can indicate particular halftone screen types, such as dot screens, line screens, stochastic screens or error diffusion. The pixel value mappings are typically implemented as Look-Up Tables (LUTs), and the LUTs of the present invention are optimized for the various halftone classes. Generation of the LUTs, or other pixel-value mappings, is non-trivial in that such mappings are normally applied to contone images and not to blurred halftoned images. The pixel-value mappings of the present invention are derived via an iterative process. Alternatively, a model for this modulated image type is used.

Abstract translation: 公开的是图像路径，其有利地使用半色调分类来选择灰度管理和颜色管理操作中的适当映射。 扫描仪中生成的标签有助于识别不同类别的半色调。 从几个像素值映射中选择一个来提供适当的补偿。 也就是说，基于来自扫描仪的半色调分类标签来选择颜色管理模块内的一维和多维像素值映射。 标签是指示“低频半色调”和“不LFHT”的一个位，或者更优选地，标签是多位，指示包含输入半色调的频率的频率仓。 此外，多位标签可以指示特定的半色调屏幕类型，例如点屏幕，线屏幕，随机屏幕或错误扩散。 像素值映射通常被实现为查找表（LUT），并且本发明的LUT针对各种半色调类进行了优化。 LUT的生成或其他像素值映射是不重要的，因为这样的映射通常被应用于连续色调图像而不是模糊的半色调图像。 本发明的像素值映射通过迭代处理得到。 或者，使用用于该调制图像类型的模型。