I fully agree on the abuse of the 'resolution' term, yet that is the term used in TIFF header tags: http://www.awaresystems.be/imaging/tiff/tifftags/xresolution.html, although stupidly enough they only allow inches or centimeters as units. Open Microscopy Environment, which are the ones trying to standardize things in my field of research have tags called: PhysicalSizeX, PhysicalSizeY, PhysicalSizeZ, which I find more explicit. As a skimage (very happy) user, I must say I find **very** convenient that vanilla ndarrays are accepted throughout the libary, because image metadata is a problem best kept away from the calculus, except in issues of the 'sampling case' type, where I agree it is nicer to have it as a clear function argument. Best, Guillaume On 22/09/2013 19:48, Almar Klein wrote:
On 22 September 2013 05:57, Juan Nunez-Iglesias <jni.soma@gmail.com <mailto:jni.soma@gmail.com>> wrote:
On Sun, Sep 22, 2013 at 1:20 PM, Jaime Fernández del Río <jaime.frio@gmail.com <mailto:jaime.frio@gmail.com>> wrote:
So a pixel replicated TIFF image has twice the resolution, as per the above official definition, not the same resolution with twice the sampling.
Even in this case, what we call sampling/spacing is the *inverse* of that definition of resolution.
I think strictly speaking, the term "resolution" is a measure for visibility of detail. The term is used a lot to simply denote the *number* of pixels, e.g. 800x600, 1024x768, etc. Spacing/sampling is really just a a measure (usually in mm) that specifies the distance between two pixels. If you know the number of pixels, and the sampling, you know the image size in physical units.
- Almar -- You received this message because you are subscribed to the Google Groups "scikit-image" group. To unsubscribe from this group and stop receiving emails from it, send an email to scikit-image+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
As a skimage (very happy) user, I must say I find **very** convenient that vanilla ndarrays are accepted throughout the libary, because image metadata is a problem best kept away from the calculus, except in issues of the 'sampling case' type, where I agree it is nicer to have it as a clear function argument.
Just to be clear, I think skimage should *always* accept vanilla ndarrays, and I agree that functions that can deal with anisotropy should have an explicit (and optional) "sampling" argument. I think my suggestion would be that such a function should check if the array has a sampling attribute, and use that if the sampling argument is not given. In that way, we could do "im = imerode(imdilate(my_image_with_sampling_attr)", and things would just work in the correct manner. - Almar On 22 September 2013 05:57, Juan Nunez-Iglesias <jni.soma@gmail.com> wrote:
On Sun, Sep 22, 2013 at 1:20 PM, Jaime Fernández del Río < jaime.frio@gmail.com> wrote:
So a pixel replicated TIFF image has twice the resolution, as per the above official definition, not the same resolution with twice the sampling.
Even in this case, what we call sampling/spacing is the *inverse* of that definition of resolution.
I think strictly speaking, the term "resolution" is a measure for visibility of detail. The term is used a lot to simply denote the *number* of pixels, e.g. 800x600, 1024x768, etc. Spacing/sampling is really just a a measure (usually in mm) that specifies the distance between two pixels. If you know the number of pixels, and the sampling, you know the image size in physical units. - Almar -- You received this message because you are subscribed to the Google Groups "scikit-image" group. To unsubscribe from this group and stop receiving emails from it, send an email to scikit-image+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out. --
You received this message because you are subscribed to the Google Groups "scikit-image" group. To unsubscribe from this group and stop receiving emails from it, send an email to scikit-image+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
participants (2)
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Almar Klein -
Guillaume Gay