Draft: Add 'dynamic colormap' mode #4271

payno · 2025-04-14T09:27:47Z

close #4263

This reverts commit 46ce9e5.

This reverts commit a08e507.

…sition

lesaintjerome · 2025-04-14T13:23:17Z

Define the area (near) the mouse to be used to compute the colormap
If possible display the region near the mouse where the mode (this is implemented by setting z=1 in the addShape() function.
- Remove the blue rectangle when DynamicColormap mode is deactivated.
Add a dedicated icon for this new mode
Add documentation
Clean the code
Add test
Link this mode to the ColormapDialog
Add shortcut to activate the mode.

lesaintjerome · 2025-04-14T14:28:12Z

It would be more relevant to adjust the colormap over the ROI of screen pixels (rather than image pixels).

… values

…oom.

lesaintjerome · 2025-04-15T16:03:15Z

It would be more relevant to adjust the colormap over the ROI of screen pixels (rather than image pixels).

Shall I try to implement? Actually, I am not entirely convinced by this. If zoomed in, one image pixel might be represented by a 20x20 square of screen pixels. Adjusting over this does not make sense...

lesaintjerome · 2025-04-15T16:04:17Z

For some reason, it seems that no check is done on the PR. There were some yesterday (and they failed, for reason that are beyond my understanding...). No more today.

lesaintjerome · 2025-04-15T16:07:28Z

@t20100 : I asked the review to you, because Henri opened the PR... We discussed with Henri: I ask a review as a first iteration.

payno · 2025-04-16T12:40:49Z

It would be more relevant to adjust the colormap over the ROI of screen pixels (rather than image pixels).

Shall I try to implement? Actually, I am not entirely convinced by this. If zoomed in, one image pixel might be represented by a 20x20 square of screen pixels. Adjusting over this does not make sense...

IMO it can be done in another PR. Let's try to have the good structure and something fairly working first. Then it can be modified later.

payno · 2025-04-16T12:41:09Z

@t20100 : I asked the review to you, because Henri opened the PR... We discussed with Henri: I ask a review as a first iteration.

😆 I can do the pre-review

payno · 2025-04-16T12:45:14Z

o check is done on the PR. There were some yesterday (and they failed, for reason that are beyond my understanding...). No more today.

Indeed this is a bit weird.

examples/dynamic_colormap.py

payno · 2025-04-16T13:34:47Z

src/silx/gui/dialog/ColormapDialog.py

+        # dynamic colormap
+        self._dynamicColormap = qt.QPushButton(self)
+        self._dynamicColormap.setCheckable(True)
+        self._dynamicColormap.setEnabled(False)
+        self._dynamicColormap.setText("Dynamic colormap")
+        self._dynamicColormap.setIcon(icons.getQIcon("add-shape-rectangle"))
+        self._dynamicColormap.setCheckable(True)
+        # self._dynamicColormap.toggled.connect(
+        #    self._handleDynamicColormap, type=qt.Qt.QueuedConnection
+        # )
+


All of this is unused at the moment. It should be either removed or fully integrated on the ColormapDialog. As a reminder the ColormapDialog is this widget:

IMO better to remove this code first and have the processing working as a PlotAction

Note: in case you want to integrate it 'setCheckable` seems repeated.
'

OK. I remove it completely since I see no point in having a checkbox in this dialog which does nothing but what the icon in the widget toolbar does.

Yes I think removing is the best. But indeed those are covering two 'different' uses cases / concept.

The QAction
Each PlotWindow (like Plot2D) can define a set of action tunable by the users. By default not all are here (and yours might not be part of the default one - to be discussed).
But anyway everyone defining PlotWindow can define which action are present on the toolbar or not.

The ColorbarDialog
Well this widget is common to everyone and everyone will access to all the options for now. IMO at the end we should find your option. But again it can come in a second step. As we might also want to define the shape; the radius...

src/silx/gui/plot/PlotInteraction.py

payno · 2025-04-16T13:38:10Z

src/silx/gui/plot/PlotInteraction.py

+    ROI_SIZE = (10, 10)  # (y,x). The ROI <<radius>>
+
+    @staticmethod
+    def compute_vmin_vmax(data, dataPos):


Did you consider moving this API from public to protected API ?

Will do. By this, you simply mean renaming it _compute_vmin_vmax() right?

src/silx/gui/plot/PlotInteraction.py

payno · 2025-04-16T13:56:15Z

src/silx/gui/plot/PlotInteraction.py

+        # Set new min and max
+        colormap.setVRange(vmin, vmax)
+        item.setColormap(colormap)


I misslead you sorry, indeed the update will be applied even if 'item.setColormap(colormap)' is not called. I had the old object in mind my bad 🙏

Suggested change

# Set new min and max

colormap.setVRange(vmin, vmax)

item.setColormap(colormap)

# Set new min and max

colormap.setVRange(vmin, vmax)

src/silx/gui/plot/PlotWidget.py

payno · 2025-04-16T13:59:08Z

src/silx/gui/plot/PlotWidget.py

+        elif key == qt.Qt.Key_W:
+            self.setInteractiveMode("dynamic_colormap")
+        elif key == qt.Qt.Key_P:
+            self.setInteractiveMode("pan")
+        elif key == qt.Qt.Key_Z:
+            self.setInteractiveMode("zoom")


keyboard shortcut could be added to the PR description. It could be useful to get them back quickly... and to discuss them.
On this PR I would only propose a shortcut for the 'dynamic_colormap'. Others can be propose on dedicated PR

Not sure we want to add this to PlotWidget, at least without a review of all keyboard shortcuts + it's easy to add in an application

I understand the point, but it's really a key feature to me: to make it light... : in that respect, adding the icon in the colormap widget would not make much sense IMO. But maybe it is independent where the icon is and how to activate the interaction mode...

But maybe it is independent where the icon is and how to activate the interaction mode...

Yes!

it's really a key feature to me

Sure, but this doesn't mean it is a key feature for other usage of PlotWidget (e.g., when plotting curves). That's why I propose to start by having this shortcut in your application rather than as a default in PlotWidget

src/silx/gui/plot/actions/mode.py

payno · 2025-04-16T14:05:42Z

src/silx/gui/plot/test/test_plotinteraction.py

+class TestSelectDynamicColormap():
+
+    def test_evaluate_roi(self):
+        """Test evaluate_roi() method"""
+        plot = PlotWidget()
+        plot.setInteractiveMode("dynamic_colormap", shape="rectangle", label="test")
+
+        interaction = plot.getInteractiveMode()
+        assert interaction["mode"] == "dynamic_colormap"
+        assert isinstance(plot.interaction()._eventHandler, DynamicColormapMode)
+
+        # Test with a rectangle
+        roi = numpy.arange(484).reshape((22,22))
+        vmin, vmax, bb_x, bb_y = DynamicColormapMode.compute_vmin_vmax(roi,(11,11))
+        assert vmin == 23 and vmax == 460 and bb_x == (1,1,21,21) and bb_y == (1,21,21,1)
+
+        roi = numpy.arange(484).reshape((22,22))
+        vmin, vmax, bb_x, bb_y = DynamicColormapMode.compute_vmin_vmax(roi,(0,0))
+        assert vmin == 0 and vmax == 207 and bb_x == (0,0,10,10) and bb_y == (0,10,10,0)
+
+        roi = numpy.arange(484).reshape((22,22))
+        vmin, vmax, bb_x, bb_y = DynamicColormapMode.compute_vmin_vmax(roi,(21,21))
+        assert vmin == 253 and vmax == 483 and bb_x == (11,11,22,22) and bb_y == (11,22,22,11)


new test must be done with pytest instead of unittest.
And maybe it could be split into two tests instead of one.

So more something like

def test_dynamic_colormap_interaction(qapp): plot = PlotWidget() plot.setInteractiveMode("dynamic_colormap", shape="rectangle", label="test") interaction = plot.getInteractiveMode() assert interaction["mode"] == "dynamic_colormap" assert isinstance(plot.interaction()._eventHandler, DynamicColormapMode) def test_dynamic_colormap_vmin_vmax_calculation(qapp): roi = numpy.arange(484).reshape((22,22)) vmin, vmax, bb_x, bb_y = DynamicColormapMode.compute_vmin_vmax(roi,(11,11)) assert vmin == 23 and vmax == 460 and bb_x == (1,1,21,21) and bb_y == (1,21,21,1) roi = numpy.arange(484).reshape((22,22)) vmin, vmax, bb_x, bb_y = DynamicColormapMode.compute_vmin_vmax(roi,(0,0)) assert vmin == 0 and vmax == 207 and bb_x == (0,0,10,10) and bb_y == (0,10,10,0) roi = numpy.arange(484).reshape((22,22)) vmin, vmax, bb_x, bb_y = DynamicColormapMode.compute_vmin_vmax(roi,(21,21)) assert vmin == 253 and vmax == 483 and bb_x == (11,11,22,22) and bb_y == (11,22,22,11)

Not sure I understand the comment on unittest vs. pytest. OK for the split. DOne.

Co-authored-by: payno <[email protected]>

t20100 · 2025-04-17T10:27:20Z

It would be more relevant to adjust the colormap over the ROI of screen pixels (rather than image pixels).

Shall I try to implement? Actually, I am not entirely convinced by this. If zoomed in, one image pixel might be represented by a 20x20 square of screen pixels. Adjusting over this does not make sense...

You could have a mix of both: use a 20x20 square on screen and then make sure it is at least 20x20 pixels in the image

t20100

There's a structural issue of where to implement this feature: IMO it should be implemented "on-top" of PlotWidget rather than in PlotInteraction.py.

There's also a question of where this feature should be provided: ColormapDialog, ImageToolBar, a QAction that is not included in plots by default ? I would suggest to give a try to the colormap dialog since it is related to it.. even if there's quite a lot of things already.

Finally the icon does not convey the meaning of a dynamic colormap IMO.
Use https://github.com/silx-kit/silx/blob/main/src/silx/resources/gui/icons/image-select-box.png ?

t20100 · 2025-06-30T11:23:16Z

examples/dynamic_colormap.py

+def main():
+    app = qt.QApplication([])
+
+    # Create the ad hoc plot widget and change its default colormap
+    x = numpy.zeros((100, 100),dtype=numpy.float32)
+    x[:50,:50] = numpy.random.randn(50,50)
+    x[:50,50:] = 10 * numpy.random.randn(50,50)
+    x[50:,:50] = 100 * numpy.random.randn(50,50)
+    x[50:,50:] = 5 * numpy.random.randn(50,50)
+
+    example = Plot2D()
+    example.addImage(x)
+    example.show()
+
+    app.exec()
+
+
+if __name__ == "__main__":
+    main()


There is nothing specific about dynamic colormap in this code sample, I would remove it.

t20100 · 2025-06-30T11:30:55Z

src/silx/gui/plot/PlotInteraction.py

            return super().endDrag(startPos, endPos, btn)


+class DynamicColormapMode(ItemsInteraction):


PlotInteraction.py is not the place for "specific" interaction (i.e., that depends on specific items), and it's best to not add features in this module since it would benefit from a large refactoring.
I'll look for an alternative.

OK. I understand that this interaction only aims 2d plots. Then, its place could be in the ImageToolbar. In the same time, it is really an interactive mode.

Yes, it is an interaction mode so independent of the ImageToolbar.
I'll look at it an propose a way to structure this

t20100 · 2025-06-30T11:31:32Z

src/silx/gui/plot/PlotInteraction.py

+        else:
+            item = result.getItem()


Suggested change

else:

item = result.getItem()

item = result.getItem()

t20100 · 2025-06-30T11:32:29Z

src/silx/gui/plot/PlotInteraction.py

+    def _compute_vmin_vmax(data: numpy.ndarray, dataPos: tuple[float, float]):
+        """Compute the min and max values of the data in a ROI centered on (x,y)"""
+        roi_size = DynamicColormapMode.ROI_SIZE
+        idx_x, idx_y = int(dataPos[0]), int(dataPos[1])


This doesn't take care of origin and scale of the Image item

True. But it is not incompatible. In the worst case, it does not improve the local contrast. The user can choose either a specific color scale or to use that feature.

The image can have an offset from origin and a scaling so the coordinates of the plot dataPos cannot be converted directly to indices in the image array.
As it is, the local contrast will be computed on a wrong area of the image if this image has an offset or scale.

This should be handled and it should not be an issue to do so

You retrieve the data from the an item upper (on the stack).
I think this data is an instance of ImageData. If I m right you should have all your need there.

t20100 · 2025-06-30T11:34:18Z

src/silx/gui/plot/PlotWidget.py

+    # sigDynamicColormapModeChanged = qt.Signal(object)
+    # """
+    # Signal emitted when the dynamic colormap changed
+
+    # It provides the source as passed to :meth:`setInteractiveMode`.
+    # """
+


Suggested change

# sigDynamicColormapModeChanged = qt.Signal(object)

# """

# Signal emitted when the dynamic colormap changed

# It provides the source as passed to :meth:`setInteractiveMode`.

# """

t20100 · 2025-06-30T11:36:51Z

src/silx/gui/plot/PlotWidget.py

+        elif key == qt.Qt.Key_W:
+            self.setInteractiveMode("dynamic_colormap")
+        elif key == qt.Qt.Key_P:
+            self.setInteractiveMode("pan")
+        elif key == qt.Qt.Key_Z:
+            self.setInteractiveMode("zoom")


Not sure we want to add this to PlotWidget, at least without a review of all keyboard shortcuts + it's easy to add in an application

t20100 · 2025-06-30T11:37:23Z

src/silx/gui/plot/actions/mode.py

+    """QAction controlling the colormap mode of a :class:`.PlotWidget`.
+    This mode adjusts the colormap based on a small region around the 


Suggested change

"""QAction controlling the colormap mode of a :class:`.PlotWidget`.

This mode adjusts the colormap based on a small region around the

"""QAction controlling the colormap mode of a :class:`.PlotWidget`.

This mode adjusts the colormap based on a small region around the

t20100 · 2025-06-30T11:41:05Z

src/silx/gui/plot/tools/toolbars.py

+        self._dynamicColormapAction = actions.mode.DynamicColormapAction(
+            parent=self, plot=plot
+        )
+        self.addAction(self._dynamicColormapAction)
+


This will add it to all kind of plots (curves, scatters) while it only works with images, so it's not the place.
This could be added to the colormap dialog, though it is already quite crowded or the ImageToolBar... or not included in any toolbar and added by the application that wants it

Same remark as before: could be in ImageToolbar but is truly an interactive mode. On the top of that, this ImageToolbar does not seem to be used on the PlotWindow/ImageView that displays images. I can add the action in the Plot2D toolbar. But don't really know how to handle the interaction mode (hence the initial positioning in the PlotWidget/InteractionToolbar.

t20100 · 2025-06-30T11:42:03Z

src/silx/gui/plot/PlotInteraction.py

+        elif isinstance(self._eventHandler, DynamicColormapMode):
+            return {"mode": "dynamic_colormap"}
+


Let's avoid to add a "generic" interaction for a specific case

Not sure I get what is behind the 'generic' interaction. Do you suggest that we have some kind of interaction subset / categories ?
Because at the moment we need a specific interaction mode to avoid conflict with other modes.

t20100 · 2025-07-04T09:24:28Z

Here is a minimal working prototype of how to implement it without changing the internals of PlotWidget:

from typing import Any

import numpy as np

from silx.math.combo import min_max
from silx.gui import qt
from silx.gui import icons
from silx.gui.plot import items
from silx.gui.plot.items.core import PickingResult
from silx.gui.plot.PlotWidget import PlotWidget
from silx.gui.plot.actions import PlotAction
from silx.gui.plot import Plot2D


class DynamicColormapAction(PlotAction):
    def __init__(self, plot: PlotWidget, parent: qt.QWidget | None = None):
        super().__init__(
            plot,
            icon=icons.getQIcon("image-select-box"),
            text="Dynamic colormap mode",
            tooltip="Update the colormap according to the mouse position in the plot",
            triggered=self.__triggered,
            checkable=True,
            parent=parent,
        )

    def __triggered(self, checked: bool) -> None:
        plotWidget = self.plot
        if checked:
            plotWidget.sigPlotSignal.connect(self.__plotChanged)
        else:
            plotWidget.sigPlotSignal.disconnect(self.__plotChanged)

    def __pickTopMostImageData(self, x: float, y: float) -> PickingResult | None:
        for pickingResult in self.plot.pickItems(
            x,
            y,
            condition=lambda item: isinstance(item, items.ImageDataBase)
        ):
            return pickingResult
        return None
    
    def __plotChanged(self, event: dict[str, Any]) -> None:
        if event.get("event") != "mouseClicked":
            return
        
        pickingResult = self.__pickTopMostImageData(event["xpixel"], event["ypixel"])
        if pickingResult is None:
            return
        
        image = pickingResult.getItem()
        indices = pickingResult.getIndices()

        if indices is None:
            return
        
        row, col = indices[0][0], indices[1][0]

        # TODO define ROI in pixel coords and compute range accordingly
        value = image.getData(copy=False)[row, col]
        vmin, vmax = value - 10000, value + 10000

        colormap = image.getColormap()
        colormap.setVRange(vmin, vmax)


app = qt.QApplication([])
plot = Plot2D()
dynamicColormapAction = DynamicColormapAction(plot)
plot.toolBar().insertAction(plot.getColormapAction(), dynamicColormapAction)
plot.addImage(np.arange(1024.**2).reshape(1024, 1024))
plot.show()
app.exec()

It's missing:

the actually ROI-based min-max computation but that can be taken from this PR
the W keyboard shortcut that I'm not sure where to implement and at first I propose to NOT do it in silx and think about all the keyboard shortcuts at hand. This can be added in a Plot2D/PlotWidget subclass in the application in the meantime.

t20100 · 2025-07-07T07:40:59Z

Regarding where to put this feature in silx: It would make sense to me to add it to the colormap dialog since there is already 2 related options: Fixed scale on: [Visible Area] [Selection].
The colormap dialog is already quite busy... but so are the toolbars..

t20100 · 2025-07-07T07:55:42Z

BTW, here are some alternative for the implementation:

The ColormapDialog is using a RegionOfInterestManager to handle the Selection interaction. A similar approach could be used with PointROI here.
PlotWidget.setInteractiveMode("select", ...) to have a dedicated interaction mode.

Jerome Lesaint and others added 8 commits March 25, 2025 22:21

[vv-like] Dynamically adjust colormap to cursor position

a08e507

[vv-like] Zoom in and out with i/o keys.

46ce9e5

Revert "[vv-like] Zoom in and out with i/o keys."

2ebee34

This reverts commit 46ce9e5.

Revert "[vv-like] Dynamically adjust colormap to cursor position"

3d7e541

This reverts commit a08e507.

Merge branch 'main' into vvlike

fbc7b08

bootstrap new mode: update dynamically colormap according to mouse po…

c4974f7

…sition

Merge remote-tracking branch 'origin/fix_4263' into vvlike

27949b1

Dynamicl Colormap: draft implementation of a seperate mode

90be74d

Jerome Lesaint added 3 commits April 14, 2025 16:51

Remove prints, use math.combo.min_max

caade84

Remove prints.

ef931e2

Move most of the code the a testable (static) function.

f37f2ba

payno changed the title ~~Draft: bootstrap new mode: update dynamically colormap according to mouse po…~~ Draft: Add 'dynamic colormap' mode Apr 15, 2025

Jerome Lesaint added 6 commits April 15, 2025 10:51

Add a static function to compute new colormap

bd73b36

Fix propagation of interactive mode to plot widget

41ec4ee

Replace numpy.max/min with max/min

0b9db3a

Add simple test on activatation of the correct mode and check min max…

cbfc436

… values

Remove prints...

d7176f4

Add shirtcuts to the 3 interaction modes W:Dynamic cmap, P: pan, Z: z…

9a79361

…oom.

lesaintjerome self-assigned this Apr 15, 2025

lesaintjerome requested a review from t20100 April 15, 2025 16:06

payno changed the title ~~Draft: Add 'dynamic colormap' mode~~ Add 'dynamic colormap' mode Apr 16, 2025

payno changed the title ~~Add 'dynamic colormap' mode~~ Draft: Add 'dynamic colormap' mode Apr 16, 2025

payno commented Apr 16, 2025

View reviewed changes

lesaintjerome and others added 8 commits April 16, 2025 17:04

Update src/silx/gui/plot/PlotInteraction.py

c385029

Co-authored-by: payno <[email protected]>

Update src/silx/gui/plot/PlotInteraction.py

bc10794

Co-authored-by: payno <[email protected]>

Update src/silx/gui/plot/PlotInteraction.py

2fe6fca

Co-authored-by: payno <[email protected]>

Update src/silx/gui/plot/PlotInteraction.py

eccb4a1

Co-authored-by: payno <[email protected]>

Add doc to the dynamic_colormap example

2846eea

Complete doc of example

3309167

Make compute_vmin_vmax protected

1ad842a

Review by HP

308b49d

t20100 reviewed Jun 30, 2025

View reviewed changes

		return super().endDrag(startPos, endPos, btn)


		class DynamicColormapMode(ItemsInteraction):

		"""QAction controlling the colormap mode of a :class:`.PlotWidget`.
		This mode adjusts the colormap based on a small region around the

		elif isinstance(self._eventHandler, DynamicColormapMode):
		return {"mode": "dynamic_colormap"}

Draft: Add 'dynamic colormap' mode #4271

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