找到一个线中的图像文件 [英] Finding a line in an image file

问题描述

我想剪裁掉正处在一个PDF边缘的打印机标记。

I am trying to crop out the printer marks that are at the edges of a PDF.

我想借此解决这个问题的路径如下：
转换PDF成位图，然后遍历位图，并试图找到的线，那么一旦线被发现，发现这些线的边缘的坐标，将裁剪坐标的坐标刚发现

The path i want to take to solve this problem is as follows: Convert PDF into a bitmap and then traverse the bitmap and try to find the lines, then once the lines are found, find the coordinates of the edges of these lines, set the cropping coordinates to the coordinates just found.

但是，这种弹出在我的脑海这种方法的问题是如何知道什么时候结束线条和实际页面开始。如何区分字母线。

However the problems that pop up in my mind with this approach is how to know when the lines end and the actual page starts. How to differentiate lines from letters.

我如何克服这些障碍，还是有更好的方法来从PDF裁剪出来的打印机标记？

How do I overcome these hurdles, or is there a better way to crop out the printer marks from a PDF?

推荐答案

有就是对所有PDF文件的工作没有通用的答案，但也有一些是由现有的图形艺术解决方案，实现了一些有用的策略，如卡拉斯pdfToolbox（看着它，我与本产品）或相关的PitStop。围绕若干事实的战略中心：

There is no general answer that works for ALL PDF files, however there are a few useful strategies that are implemented by existing solutions for graphics arts such as callas pdfToolbox (watch it, I'm associated with this product) or PitStop. The strategies center around a number of facts:

• 修剪和出血标记通常是简单的线条（虽然薄矩形有时也同样使用）。他们是短而直（水平或垂直）。

• trim and bleed marks are usually simple lines (though thin rectangles are sometimes used as well). They are short and straight (horizontal or vertical).

这些标记通常是在特定的颜色绘制。任一的CMYK的颜色设置为100％，100％，100％，100％或 - 更常见 - 一个特殊的专色称为所有。你几乎可以保证这一点，因为这些标志必须出现在每一个印刷分离（抱歉技术印刷术语，如果你不熟悉它们）。

These marks are usually drawn in specific colours. Either CMYK with the color set to 100%, 100%, 100%, 100% or - more commonly - a special spot color called "All". You're almost guaranteed of this because these marks need to show up on every printed separation (sorry for the technical printing terms if you're not familiar with them).

这些标记通常是对称镜像。你不是在寻找一个标志 - 你正在寻找一组人，这通常与认识有很大帮助。但是当心，你没有不把绝对精确标记坏的应用相混淆。

These marks normally are mirrored symmetrically. You're not looking for a single mark - you're looking for a set of them and this typically helps with recognition a lot. Watch out however that you're not confused by bad applications which don't place marks with absolute accuracy.

最后，但也许在你的应用程序并不重要，不同区域实际上可以与不同类型的标记工作。日本的装饰和出血标记，例如看起来比欧洲或美国的标志完全不同。

Lastly but perhaps not important in your application, different regions can actually work with different types of marks. Japanese trim and bleed marks for example look completely different than European or US marks.

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