Distinguishable shades of grey
From this paper:
http://rsif.royalsocietypublishing.org/content/early/2012/09/22/rsif.2012.06... The following quote (emphasis mine): Humans possess three cone visual pigments for conveying colour information that is said to allow humans to be able to detect approximately 10 million unique colours [8,9] but only distinguish about 30 shades of grey [10]. (Let's ignore recent movies of dubious merit in this discussion. =P) In the new MPL imshow plugin (which I recently wrote), we switch from grayscale to cubehelix when the dynamic range is too low to be displayed on a common monitor (1/255): https://github.com/scikit-image/scikit-image/blob/master/skimage/io/_plugins... Maybe the threshold should be when the difference is imperceptible to most humans (1/30)? Juan.
On 2015-02-21 15:53:47, Juan Nunez-Iglesias <jni.soma@gmail.com> wrote:
In the new MPL imshow plugin (which I recently wrote), we switch from grayscale to cubehelix when the dynamic range is too low to be displayed on a common monitor (1/255):
Importantly, it should be clear and intuitive to users when the switch happens. Why do we not always use cubehelix? Apart from that it is a rather ugly colormap. Stéfan
Any time that cubehelix is used, a colorbar is shown. So I think it's clear to the user what is going on. As to why we don't always use it, the fact is that when people load a grayscale (natural) image, they expect it to appear in grayscale. This is true of most of our examples, e.g., coins, camera. plt.imshow shows camera in jet by default, which is appalling *and* surprising to the user. Cubehelix would be merely surprising. =P On the other hand, it's generally unlikely that an image that shows no perceptually distinguishable shades of grey is actually a natural image. In those cases, I think it's appropriate to show cubehelix. (Or another suitable colormap. But I didn't want to wait until mpl made their fancy new one.) The key here is that imshow is a command made interactively to *explore one's data*. One wants to know at a glance what is going on. It's infuriating to load up an image and have it appear as a black rectangle because its range in 16-bit grayscale is really low. Then I have to go type a much longer command to get it to show the way I want. So I think in these cases a little magic is justified that will get people the result they want in one short command that will work as expected most of the time. — Sent from Mailbox On Sun, Feb 22, 2015 at 7:32 PM, Stefan van der Walt <stefanv@berkeley.edu> wrote:
In the new MPL imshow plugin (which I recently wrote), we switch from grayscale to cubehelix when the dynamic range is too low to be displayed on a common monitor (1/255): Importantly, it should be clear and intuitive to users when the switch happens. Why do we not always use cubehelix? Apart from
On 2015-02-21 15:53:47, Juan Nunez-Iglesias <jni.soma@gmail.com> wrote: that it is a rather ugly colormap. Stéfan -- 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/d/optout.
As a side note, default jet is going away 'soon'. Tom On Sun Feb 22 2015 at 8:31:01 AM Juan Nunez-Iglesias <jni.soma@gmail.com> wrote:
Any time that cubehelix is used, a colorbar is shown. So I think it's clear to the user what is going on.
As to why we don't always use it, the fact is that when people load a grayscale (natural) image, they expect it to appear in grayscale. This is true of most of our examples, e.g., coins, camera. plt.imshow shows camera in jet by default, which is appalling *and* surprising to the user. Cubehelix would be merely surprising. =P
On the other hand, it's generally unlikely that an image that shows no perceptually distinguishable shades of grey is actually a natural image. In those cases, I think it's appropriate to show cubehelix. (Or another suitable colormap. But I didn't want to wait until mpl made their fancy new one.)
The key here is that imshow is a command made interactively to *explore one's data*. One wants to know at a glance what is going on. It's infuriating to load up an image and have it appear as a black rectangle because its range in 16-bit grayscale is really low. Then I have to go type a much longer command to get it to show the way I want. So I think in these cases a little magic is justified that will get people the result they want in one short command that will work as expected most of the time.
— Sent from Mailbox <https://www.dropbox.com/mailbox>
On Sun, Feb 22, 2015 at 7:32 PM, Stefan van der Walt <stefanv@berkeley.edu
wrote:
On 2015-02-21 15:53:47, Juan Nunez-Iglesias <jni.soma@gmail.com> wrote:
In the new MPL imshow plugin (which I recently wrote), we switch from grayscale to cubehelix when the dynamic range is too low to be displayed on a common monitor (1/255):
Importantly, it should be clear and intuitive to users when the switch happens. Why do we not always use cubehelix? Apart from that it is a rather ugly colormap.
Stéfan
-- 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/d/optout.
-- 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/d/optout.
@tacaswell, I'm aware, hence,
But I didn't want to wait until mpl made their fancy new one
=) How are those discussions going? Is there still going to be a custom fancy new cmap? Or are people thinking of settling into an existing map? Even Matlab is done with jet now, thankfully. (Not a huge fan of parula, though. But it's an improvement.) On Sun, Feb 22, 2015 at 7:32 PM, Stefan van der Walt <stefanv@berkeley.edu> wrote:
In the new MPL imshow plugin (which I recently wrote), we switch from grayscale to cubehelix when the dynamic range is too low to be displayed on a common monitor (1/255): Importantly, it should be clear and intuitive to users when the switch happens. Why do we not always use cubehelix? Apart from
On 2015-02-21 15:53:47, Juan Nunez-Iglesias <jni.soma@gmail.com> wrote: that it is a rather ugly colormap. Stéfan -- 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/d/optout.
participants (3)
-
Juan Nunez-Iglesias -
Stefan van der Walt -
Thomas Caswell