Part of a series – Color Managed Workflow
Today – Seeing differences between two colors
Summary – How much can colors differ (between monitor and print; between camera capture and post-processing displays, etc.) before you can notice the difference? This difference, jnd, may make or break your efforts to get correct image colors. This post illustrates jnd by comparing possible camera vs monitor color differences.
I recently asked when is an image “good enough”
How about a similar question
When is the match of two colors “close enough”?
Welcome to the world of jnd
(I’m not making up the acronym)
Roll mouse over the image to see the after version
Shadow recovery in the cliff face
Acadia National Park
DND (Definitely Noticeable Differences); I did make this one up 😉
Note: Today’s color match question is somewhat related to
BUT – different
The colored blocks in the IQ test
Were noticeably different in terms of hue
The test challenge was to put them in “hue order”
jnd addresses the related question of
How different must two colors be before
We even notice that they are different
Without all of the color-geek-speak details –
Color differences can be measured & quantified objectively
Based on such measurements, tests with viewers established
How large the difference between two colors must be
Before the difference is noticed (subjective)
This is the jnd for colors
jnd also is used in other applications, e.g. music
Tests put the color jnd value in the range of
A color mismatch between 2.3 and 6
(I’ll spare you the details & illustrate this below;
suffice to say if the mismatch is above 6
Viewers will probably notice it)
The example uses sRGB & Adobe RGB 1998 spaces for illustration
To remind you of how these two space compare
Fig. 2, below, shows jnd for sRGB vs Adobe RGB color spaces
Well, your camera typically will use one or the other
Your monitor most often also uses one or the other
Fig. 2 shows the difference between
What your camera captured and your monitor displays
WHEN these two devices aren’t using the same color space
Should you care?
I sure would!
If your post processing software reports
“Profile Mismatch” (or a similar alert)
When you open an image
This is what it’s alerting you to 😦
Click for Full Screen
The horizontal bar near the bottom is the
Key for the differences shown in the main image above it
For example, the black square has a difference of 9 (very noticeable)
It’s the difference between the two space’s green
Look at Figure 1 to see WHY the large difference in greens
Of course, the differences don’t have to be so noticeable
That’s where profiles enter the picture (a pun?)
The color differences in this “after profile” example
Range from 0 to 0.025, as compared to
0 to 9+ when we ignored the color space mismatch
Which would you prefer? 😉
This is a tease for the next Color Management post
Profiles – what they are & what they do
In a few days after the glaze clears from your eyes 😉
I’m hoping to convince you that
You should know & care about color management
If you’ve learned something, pass it on….
This post illustrates my posting goal (not always achieved)
To provide useful photography improvement related information that won’t be found on hundreds of other sites; stand out from the crowd a little
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