公开(公告)号：US5731818A

公开(公告)日：1998-03-24

申请号：US610779

申请日：1996-03-04

申请人： Shijie Wan ,  James R. Sullivan

发明人： Shijie Wan ,  James R. Sullivan

IPC分类号： H04N9/79 ,  H04N1/46 ,  H04N1/60 ,  G06T11/40

CPC分类号： H04N1/6058

摘要： An efficient method for gamut clipping based on user-defined constraints on lightness and hue by: a) defining a color gamut surface of an output device using a gamut descriptor; b) specifying a search range based on maximum tolerances for lightness and hue changes; and, c) for each input color data point outside the gamut, mapping the data point to the closest point in a portion of the gamut surface specified by the search range.

摘要翻译： 基于用户对亮度和色调的限制的色域限幅的有效方法是：a）使用色域描述符定义输出设备的色域表面; b）根据亮度和色相变化的最大公差指定搜索范围; 并且c）对于色域外部的每个输入颜色数据点，将数据点映射到由搜索范围指定的色域表面的一部分中的最近点。

公开(公告)号：US5721572A

公开(公告)日：1998-02-24

申请号：US634685

申请日：1996-04-18

申请人： Shijie Wan ,  Kevin Edward Spaulding

发明人： Shijie Wan ,  Kevin Edward Spaulding

IPC分类号： H04N1/60 ,  G06T15/00

CPC分类号： H04N1/6016 ,  H04N1/6058

摘要： A device gamut boundary surface in a device independent color space (DICS) is defined by a set of small triangles. Each triangle in the DICS corresponds to a triangle on the surface of a 3D or 4D color cube in a device dependent color space (DDCS). The triangles in the DICS are derived based on a look-up table which can be obtained by measuring a set of color patches produced from the given device. A small set of carefully selected gamut boundary points in the DICS are determined, and their corresponding points or signals on the surface of the color cube in the DDCS are computed. These data are stored in a table called a gamut descriptor. Points in a gamut descriptor can be determined by a convex polyhedral cone inclusion process, and their corresponding points in the DDCS can be determined by triangle interpolation. The gamut descriptor usually includes gamut boundary points at a number of lightness layers along a series of predetermined hue angles. Gamut descriptor is a compact representation of gamut boundary. The point distribution pattern in a gamut descriptor provides useful information for determining in-gamut and out-of-gamut points, and for fast mapping between color spaces in cross-media color calibration.

摘要翻译： 设备独立色彩空间（DICS）中的设备色域边界面由一组小三角形定义。 DICS中的每个三角形对应于设备依赖颜色空间（DDCS）中3D或4D颜色立方体的表面上的三角形。 DICS中的三角形是基于查找表得出的，该查找表可以通过测量从给定设备产生的一组色块来获得。 确定DICS中一小组仔细选择的色域边界点，并计算其在DDCS中颜色立方体表面上的对应点或信号。 这些数据存储在称为色域描述符的表中。 色域描述符中的点可以通过凸多边形锥包含过程来确定，并且它们在DDCS中的对应点可以通过三角插值来确定。 色域描述符通常在沿着一系列预定色调角的多个亮度层上包括色域边界点。 色域描述符是色域边界的紧凑表示。 色域描述符中的点分布模式提供了确定色域和色域外的有用信息，以及跨媒体色彩校准中颜色空间之间的快速映射。

公开(公告)号：US5491568A

公开(公告)日：1996-02-13

申请号：US260134

申请日：1994-06-15

申请人： Shijie Wan

发明人： Shijie Wan

IPC分类号： G03F3/08 ,  H04N1/60 ,  H04N1/46

CPC分类号： H04N1/6033

摘要： A digital color reproduction apparatus of the type having a scanner for scanning a color image to produce scanner color signals representing the color image, a digital image processor for processing the scanner color signals to produce printer color signals, and a printer responsive to the printer color signals for reproducing the color image is said to be "closed" when the original color image and the reproduced color image are on the same medium. For a closed color reproduction system, the color transform from scanner color signals to printer color signals can be implemented using the tri-linear interpolation based on a 3D calibration lookup table. The 3D calibration lookup table can be derived automatically by: a) determining the relationship between equal printer color signals and averaged scanner color signals; b) based on the determined relationship, generating a set of color patches on the printer that are uniformly distributed in scanner color signal space; c) scanning the color patches to generate a lookup table relating printer color signals to scanner color signals; and d) inverting the lookup table to generate the calibration lookup table.

摘要翻译： 一种具有用于扫描彩色图像以产生表示彩色图像的扫描仪颜色信号的扫描器的类型的数字彩色再现装置，用于处理扫描器颜色信号以产生打印机颜色信号的数字图像处理器以及响应于打印机颜色的打印机 当原始彩色图像和再现的彩色图像在同一介质上时，用于再现彩色图像的信号被称为“关闭”。 对于闭合色彩再现系统，可以使用基于3D校准查找表的三线性内插来实现从扫描仪颜色信号到打印机颜色信号的颜色变换。 3D校准查找表可以通过以下方式自动导出：a）确定相等的打印机颜色信号和平均的扫描仪颜色信号之间的关系; b）基于确定的关系，在打印机上产生均匀分布在扫描仪颜色信号空间中的一组色块; c）扫描色块以产生将打印机颜色信号与扫描器颜色信号相关联的查找表; 以及d）反转查找表以产生校准查找表。

公开(公告)号：US5452112A

公开(公告)日：1995-09-19

申请号：US217782

申请日：1994-03-25

申请人： Shijie Wan ,  Anthony J. Leone

发明人： Shijie Wan ,  Anthony J. Leone

IPC分类号： H04N1/04 ,  H04N1/46 ,  H04N1/60 ,  H04N1/00 ,  G03F3/08

CPC分类号： H04N1/6033

摘要： A method of calibrating a color image reproduction system in the field is provided. The color image reproduction system includes a color input scanner for generating a color digital image, a digital image processor for applying a color transform to the color digital image to produce a transformed color digital image and, and a digital color printer for printing the transformed color digital image. The calibration method includes the steps of: a) providing a set of calibration tools developed on a representative system, the tools including a scanning target, a first reference file recording the response of a scanner to the scanning target in the representative system, an image file for producing a test pattern, and a second reference file recording the response of the scanner in the representative system to the test pattern printed on the printer in the representative system; and b) employing the calibration tools to calibrate the color image reproduction system in the field, by: 1) scanning the scanning target in the color scanner to produce a first test file; 2) employing the first test file and the first reference file, to generate a scanner calibration table; 3) sending the image file to the color printer to produce a second test pattern; 4) scanning the second test pattern in the color scanner and processing the output of the color scanner through the scanner calibration table to produce a second test file; and 5) employing the second test file and the second reference file to generate a printer calibration table.

摘要翻译： 提供了一种在现场校准彩色图像再现系统的方法。 彩色图像再现系统包括用于产生彩色数字图像的彩色输入扫描器，用于将颜色变换应用于彩色数字图像以产生经变换的彩色数字图像的数字图像处理器，以及用于打印变换颜色的数字彩色打印机 数字图像。 校准方法包括以下步骤：a）提供在代表性系统上开发的一组校准工具，所述工具包括扫描目标，将扫描器的响应记录到代表系统中的扫描目标的第一参考文件，图像 用于产生测试图案的文件和将代表系统中的扫描仪的响应记录到代表系统中打印在打印机上的测试图案的第二参考文件; 以及b）使用校准工具来校准现场的彩色图像再现系统，方法是：1）扫描彩色扫描器中的扫描目标以产生第一测试文件; 2）采用第一测试文件和第一参考文件，生成扫描器校准表; 3）将图像文件发送到彩色打印机以产生第二测试图案; 4）扫描彩色扫描器中的第二测试图案并通过扫描仪校准表处理彩色扫描器的输出，以产生第二测试文件; 以及5）采用第二测试文件和第二参考文件来生成打印机校准表。