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Frequently Asked Questions (FAQs):


Important note: When not specified, these statements are for the PRO version. These statements may not apply to other versions depending on the limitations they have with respect to the PRO version. These limitations can be found on the download page of the official website.


Use and capabilities:

How to compare pdf files with Kiwi?


Load each the two files using the top left button of each panel. Set the comparison by adjusting the different options and then click the compare button. After comparison is completed, you can move from one difference to the next/previous using down/up arrow buttons located in the top panel. Results can be printed then to pdf files.


What type of differences does Kiwi show?


It depends on which comparison mode you use:


In this mode format is not reviewed (fonts, margins, spaces…), it´s intended for people who are concerned only with content.

At the moment kiwi compares bitmaps images, but not vector graphics.



Can Kiwi compare word or excel documents?

Kiwi can only load pdf files, but you can export/print other type of files to pdf, using software that can handle these filetypes, and then you can compare them with Kiwi.


Can Kiwi detect changes in images?


Yes, Kiwi can detect changes in images. In the Appearance Comparison mode changes in every kind of image or graphic are detected, as it works with pixels. In the Content Comparison it detects changes in images if they are of the usual type bitmap (nowadays it can´t detect changes in vectorial graphics). In this case it detects same type of changes in images than those detected in text (modification, insertion, deletion or movement).


Possible problems:


When comparing 2 files, many things are highlighted as changes, but in fact they are not. Why?


Most of the times it´ss due to a different codification of both pdf files when they were created. If files have been created by different software applications or using different drivers to export to pdf format, sometimes resultant internal structure of the pdf files can be very different, even if external appearance is the same.

You can guess if it´s your case trying to select the text in both documents using other program and paste it in a text document. If resultant texts are different it means that the documents have been codified in a different way. In that case, Kiwi is also going to obtain different texts when reading them, and conclude they are different. If possible, try to generate again the two pdf files using the same software to avoid this issue.


Headers and footers are shown as changed, but they´re not. Why?


It is probably due to a lack of differentiation in the internal structure of the pdf between what is header and footer and what is the rest of the text, all being treated as text. In this case Kiwi will read the text in the order in which it is encoded in the pdf without distinguishing between header and footer. Note that in some cases the header and footer texts appear together in the internal structure of the document, before or after the rest of the text on the page, which may confuse the comparator in the order of its reading.

In the corners of the documents there are small squares that can be slipped to reduce the area of the document that is going to be compared in the comparing content mode. You can use them to leaf out headers, footers and lateral margins in order to obtain a relevant and clear result.


It takes a long time comparing big documents. Can it be reduced?


Kiwi use advanced algorithms to detect more type of changes than other programs, and obtain a more accurate and relevant result. It makes greater, in many cases, the time required to complete the process. As the required time increases more than proportionally with the number of pages, an effective way to reduce it is to divide comparison in several parts, comparing chapters or group of chapters.

If it takes a long time comparing even tens of pages, it may be that the computer used is old, or memory assigned for Java applications is very low. On this last case you should look in the Java documentation how to increase in your computer the Maximum Heap Size assigned for Java applications.

Finally you can change settings in the Comparing Options menu in the software to reduce the workload required.


There is text underlined, but it seems to be identical in both documents. Why?


By default Kiwi uses underline to indicate that the text has been moved within the document. You can change the way text movements are shown changing the settings in de Comparing Options and perform another comparison in order to don´t highlight theses type of changes or to show it highlighted as changed text.


I can´t leave out headers, footers and lateral margins in Appearance Comparing mode. Why?


This mode compares pages pixel by pixel, and it would be difficult to define by hand identical areas beginning at the same point, in order to compare exactly the same pixels, which would result in the appearance of differences detected that aren´t real differences. May be Kiwi could handle it in later versions.