Setting fill colors in shapes

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Level 1

58 points

Setting fill colors in shapes

This seems like a rather obscure bug. I am using Pages in page layout mode and prearing a reference sheet of paint colours. This consists of drawing rectangular shapes and setting the fill colour to a particular HSB spec (e.g. 347-26-60) using the Colors panel. If I then go back to edit a color using the Inspector panel (by clicking on image/fill) the colour displayed in the color panel has changed (to 348-32-54 in the above example) in a subtle way. However, if I use the magnify glass in the Color panel to 'read' the colour of the shape it reads correctly as the colour I set.

Can anyone explain what is going on?

iMac 2.93 GHz Intel Core 2 Duo + iPad WiFi 32GB, Mac OS X (10.7), Memory: 4GB; External Firewire 1TB; FCE 4.0.1

Posted on Oct 20, 2011 7:32 AM

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Answer 1

KOENIG Yvan

Level 8

41,825 points

Oct 20, 2011 8:02 AM in response to meljturner

Given the tests which I did, it seems that the H-S-B values are treated by an algorithm storing the values as numbers from 0 to 65535

and converting them in a smaller range for use.

As the displayed values aren’t the true ones which are floating values but the rounded ones, a small offset introduced by the algorithm may give what you get.

For instance, 347.4999999 (displayed as 347) may become 347.5000001 (displayed as 348).

If my memory is OK, there is a tech note dedicated to this kind of behavior.

Yvan KOENIG (VALLAURIS, France) jeudi 20 octobre 2011 17:02:04

iMac 21”5, i7, 2.8 GHz, 4 Gbytes, 1 Tbytes, mac OS X 10.6.8 and 10.7.0

My iDisk is : <http://public.me.com/koenigyvan>

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Answer 2

meljturner Author

Level 1

58 points

Oct 20, 2011 8:18 AM in response to KOENIG Yvan

Yvan, thanks for the suggestion. I don't think its a floating point conversion issue but it may be that Pages is converting my HSB spec to RGB or CMYK then converting the result back to HSB to display the color panel. As RGB is device-specific, this may be the issue. Someone who understands how Apple treats color spaces could probably explain it better than I.

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Answer 3

KOENIG Yvan

Level 8

41,825 points

Oct 20, 2011 8:37 AM in response to meljturner

I'm sure that there is a conversion to the range 0-65535 but I forgot details.

At this time I'm running under 10.7.2 so I haven't access to my mail's archives which are on my 10.6.8 device.

Yvan KOENIG (VALLAURIS, France) jeudi 20 octobre 2011 17:37:44

iMac 21”5, i7, 2.8 GHz, 4 Gbytes, 1 Tbytes, mac OS X 10.6.8 and 10.7.0

My iDisk is : <http://public.me.com/koenigyvan>

Please : Search for questions similar to your own before submitting them to the community

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Answer 4

Oct 20, 2011 10:53 AM in response to meljturner

OSX's ColorSync is managing your colors and converts anything outside the standard colorspaces into RGB for the screen.

This happens in all color management. If you use cmyk values they seem to stick.

Peter

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Answer 5

meljturner Author

Level 1

58 points

Oct 20, 2011 12:47 PM in response to PeterBreis0807

Peter, I'm sure you have a partial explanation but that doesn't explain why, if I use the magnifying glass in the Colour Panel to sample the colour, it gives the correct HSB value (the same as I set it). Anyway, I find if I use just the Colour Panel and drag/drop a colour into the shape, and avoid using the Inspector fill method, things go a lot smoother. Thanks for your answer.

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