Chandra X-Ray Observatory
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Last modified: 26 October 2016

URL: http://cxc.harvard.edu/chips/bugs/images.html

Bugs: images & colormaps


Table of Contents

Caveats

Bugs


Caveats

Handling of NaN and Inf values

Chips converts NaN pixel values to the minimum data value (and +Inf values to the maximum data value). This may make it difficult to differentiate those values from finite pixel values.


Bugs

Missing minor tick marks for sexagesimal-formatted axes

Some minor ticks may not be rendered when an image is zoomed out and tickformat=%ra or %dec. This only appears to happen when the axis covers a large range (e.g. 10 degrees) and is relatively close to one of the poles.

As an example, there are no minor tick marks South of -60 in

[The Y axis covers more than 10 degrees, but there are no minor tick marks South of -60]

which was created with the following code

chips> add_image('broad_flux.img', ['depth', 50, 'threshold', [0, 1e-6]])
chips> set_xaxis(['tickformat', '%ra'])
chips> set_yaxis(['tickformat', '%dec'])
chips> set_axis('all', ['tickstyle', 'outside'])
chips> zoom(0.9)
chips> set_plot_aspect_ratio('fit')

Gamma correction is ignored in SAO color maps.

True color images cannot be added when using only a single red component.

This will default to being a pseudo-color image.

True color images cannot be thresholded or inverted.

Colorbars will only display a single alpha channel in the PDF output. A spectrum will have unexpected results


Last modified: 26 October 2016
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