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:
- Content comparison: Kiwi shows modifications, insertions,
deletions and translations of text content and images,
differentiating each type of change from the others. However, you
can modify the configuration parameters to get results that are more
in tune with your wishes.
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.
- Appearance comparison: Kiwi compares page to page, pixel
to pixel, to show every difference in text and graphics content and
formats. In this mode every change that make both documents
appearance different in any way is highlighted.
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).
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
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
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
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.