To comment on the following update, log in, then open the issue:
http://www.openoffice.org/issues/show_bug.cgi?id=7019
User discoleo changed the following:
What |Old value |New value
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CC|'bm,gleppert,joergwartenbe|'bm,discoleo,gleppert,joer
|rg,mox,nmailhot,pagalmes,p|gwartenberg,mox,nmailhot,p
|mike,tonygalmiche' |agalmes,pmike,tonygalmiche
| |'
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------- Additional comments from [EMAIL PROTECTED] Sun Mar 4 21:29:47 +0000
2007 -------
*CHART2: Default Colours*
"Color used well can enhance and clarify a presentation. Color used poorly will
obscure, muddle and confuse.*
-- Maureen Stone
Unfortunately, people have difficulty learning this simple fact. I just voted
for the new default pallet to be used in Chart2, yet I was NOT very impressed by
the various pallets. The last colour scheme (number 12, blue - yellow) is
probably the better one, but even this one lacks professionalism.
*What is the problem*?
As the first quote from Maureen Stone says, *too many colors* will obscure and
confuse. Therefore I will try to expand this concept further and add some
real-life examples from professional presentations.
A few remarks are needed before expanding this issue:
1.) EXAMPLES
============
I will add some examples as jpg-images to better show the reasoning for the
colours.
I attach some professional charts taken from the WHO 2005 and 2006 reports. The
full reports (some 5 - 7 MB) can be downloaded from
http://www.who.int/entity/whr/2005/whr2005_en.pdf and
http://www.who.int/whr/2006/whr06_en.pdf (while for older reports see
http://www.who.int/whr/previous/en/index.html). Please take a look at these
charts, they look really good.
2.) BLACK-WHITE
===============
Sometimes, charts get printed on black-white printers, or colour presentations
are copied on a black-white photocopying machine (quite often). Many
colour-schemes fail poorly in this instance due to poor contrast/luminosity
difference between 2 neighboring fields.
3.) PREVIOUSLY e-MAILED
=======================
2.) I e-mailed a similar post to the chart mailing list. However, presumably
because I appended some jpg-images, the post never showed up.
2'.) I sent a similar e-mail (with jpg-attachements) directly to people working
for Sun (e.g. to Ingrid Halama), but got NO response either, so it was
presumably deleted as well.
2''.) this is my third attempt and I will post it as a comment to issue 7019
(http://www.openoffice.org/issues/show_bug.cgi?id=7019). I will attach the
beforementioned jpg-images to that issue, too. This is a greatly expanded
review.
3.) TOC
=======
This document will be organised as follows:
a. INTRODUCTION
b. BAR CHARTS
b'. 2-3 Colours
b''. MONOCHROME MODEL
c. PIE CHARTS and other Chart Types
d. DEFAULT EXAMPLES
a. INTRODUCTION
===============
Colours used in a chart should clarify the chart and NOT confuse the viewer.
Unfortunately, this is difficult when choosing many colours as they 1.) tend to
distract the viewer from the relevant information and 2.) obscure some of the
colours used.
This is the reason why professional presentations never use more than 5
different colour groups (hue-groups). Actually, IF more groups seem to be
needed, there are 2 ways to resolve this issue:
- either the user does NOT recognise the essentials in the chart (to *highlight
only the essential information*), or
- (IF – rarely – the previous statement does NOT apply) use basically a *single
hue-group*
This will be further expanded for BAR-Charts and separately for the OTHER-Chart
types.
b. BAR CHARTS
=============
Bar charts are likely to contain many groups of data. A common mistake is to
draw every BAR a different colour. This is both unnecessary and obstructs the
meaning of the bar chart.
A good colour-scheme will have to distinguish between:
B1. are there only 2 groups of data: then use of 2 oppsoing colours
(significantly different hues) is OK. Also, make the luminosity different, so
that black-white printing looks good, too.
B2. are there 3-5 groups of data: selecting 3 to 5 different colours is
feasible, BUT alternatives using only 1-2 colours are equally effective.
B3. more than 5 bars: NEVER use more than 5 colour-groups!!!
To quote Maureen Stone again:
"In most design situations, the best results are achieved by limiting hue to a
palette of two or three colors, and using hue and chroma variations within these
hues to create distinguishably different colors. Such a palette is both
aesthetically pleasing and functional. It minimizes an over-dependence on hue
variation (which can cause visual clutter), and replaces it with careful control
of value and chroma. Figure 8 shows several such palettes, and their location on
the hue wheel."
-- Maureen Stone
There are some solutions to this problem:
i.) do we need to highlight *SOMETHING*?
NO => just use the same colour for every bar (*MONOCHROME*)
ii.) IF we need to highlight 1 or 2 groups of data, apply a different colour
only to those 1-2 groups (maximum colours used = 3). IF you need to highlight
more than 3 groups, you are doing something wrong.
[in the rare situation, where a bar graph is drawn for a group of 4 or more
items repeated several times, use either monochrome, or see later for
pie-charts, BUT strong consideration should be given NOT to compare 2 or more
groups of MORE THAN 4 items each]
C. PIE CHARTS (& other chart types)
=============
A similar reasoning applies to pie charts as for bar charts: NEVER use more than
5 colour-groups.
However, pie charts often have more data groups, therefore sometimes a different
solution is needed:
C1. 2 data groups => NEVER draw a pie chart with ONLY 2 segments (as the second
segment will always be (1 - first segment))
C2. 3-4(-5) data groups: use of 3-(5) different colour groups is possible
(though alternatives are equally effective)
C3. more than 5 data groups: this is tricky; obviously we can NOT use a
monochrome drawing.
HOWEVER, more than 5 different colour groups is a strong NO. Instead, use only
one colour group (rarely 2), with:
- slight hue-variations (NOTE: the next version is better)
- *contrast/luminosity* changes: 2 adjacent colours should have very different
luminosities, so that black-white printing looks OK and also viewing in colour
highlights the difference.
IF there are more than 8-10 groups of data, the user makes something wrong!!!
Some of the groups should be contracted into a single group.
Also, with more than 5 colours, some of the colours are chosen as *shades of
gray* (+ sometimes the colour black). This fits in the concept of only
luminosity changes (with sometimes colour saturation changes).
An example will be presented from the WHO report.
Other charts (like line and dot charts) bear similarity to the pie charts.
D. DEFAULT EXAMPLES
===================
I have looked to the various chart styles on the voting page. Some look
interesting, though NONE looks really professionally. If I was to choose from
the available, I'll probably prefer the last one (number 12, blue - yellow - for
which I actually voted). This is the only one to have a professional look. All
multi-colour styles just don't seem right. Please NOTE that even this one fails
for the bar chart: there are simply to many colours. Instead use either a single
colour or only 2 colours (whith the second one to highlight only important parts
of the bar chart).
Various other professional examples from WHO reports will be presented in a
second writer document attached to the previous issue.
CONCLUSIONS
===========
a.) *multi-coloured charts* actually never look professional
IF the chart contains many groups of data, instead of using dozens of colours,
consider:
i.) a *single colour* (see attached Chart_Bars_Styles_Blue.jpg)
ii.) a limited number of similar colours + shades of gray (see examples
Chart_Bars_Styles_Orange.jpg, and most other examples)
In this latter case, consider using the highest contrast colour-pair to
highlight only the important aspects of the chart. Therefore, it is really NOT
important to have dozens of colours, BUT rather a limited number of them and use
them appropriately.
b.) there is a huge difference if somebody draws a chart only with 2 groups of
data (high contrast might be OK in this case), 3-5 groups (medium contrast and
optimal colour spread) or > 5 groups (various shades/hues of same colour
interspersed with gray tones). Having more than 5 completely different (widely
differing) colours looks awfully.
c.) As a last note: I would prefer more than one colour scheme. As pointed
previously, different schemes for the BAR and PIE charts, as well as the 2
groups case, 3-5 and >5 groups case is also warranted.
Cheers,
Leonard Mada
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