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GETCLIM: Suggest appropriate values for colormap limits

version 1.3 (1.81 KB) by

Determines thresholds such that 2% of data values will be mapped to the extremes of the colormap

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getclim determines threshold values such that 2% (by default) of
values at the top and bottom of the data range will be mapped
to the extremes of the colormap.

For datasets with a few outliers that influence the range, getclim
is superior to the default behaviour of using the min and max
of the dataset.

Usage: threshVals = getclim(imdata, dataFraction)

imdata: numeric array representing an image to be displayed
dataFraction: fraction of voxels to clip at each end (default 0.02)

threshVals: column vector of values to use for clims in imshow

Example:
I = peaks(200);
min(I(:)), max(I(:)) % -6.5487, 8.1059
threshVals = getclim(I) % -4.2936, 5.8228
I2 = I;
I2(153,106) = 3*I(153,106);
min(I2(:)), max(I2(:)) % -6.5487, 23.5936
threshVals = getclim(I2) % -4.2936, 5.8228
figure
subplot(2,2,1), imshow(I, []), title('I')
subplot(2,2,2), imshow(I, threshVals), title('I+getclim')
subplot(2,2,3), imshow(I2, []), title('I2')
subplot(2,2,4), imshow(I2, threshVals), title('I2+getclim')

See also STRECHLIM, IMADJUST

Comments and Ratings (2)

Andrew Davis

Thanks for the comment, Jurgen. I agree that a single output vector makes more sense -- I've updated the file accordingly.

Jurgen

Jurgen (view profile)

A better version of matlabs stretchlim.
Better because:
- Stretchlim returns 0-1 normalized thresholds, regardless of input class.
- Stretchlim fails with int16 even though the help says it can be used
- Any data from single or double class must be in the 0-1 range.

That said, I personally prefer 1 output vector containing both values, like with stretchlim.

Updates

1.3

Output a single vector as per Jurgen's suggestion

MATLAB Release
MATLAB 7.14 (R2012a)

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