Brightness Curve Detail Control

[davidh]

There seems to be another problem with the Detail control combo box refreshing besides the one described by Winfried. When the Detail control combo box is set to Yes and then the dialog is closed with the bottom expanded, it correctly reopens expanded but with the value set to default No. The Yes/No values then remain swapped. Also the handle of the Radius slider scale sometimes disappears but will reappear by a click somewhere on the slider scale. The Reset command will not correct the situation.

One additional question. The Detail Control parameters are not saved in the .crv file. Is it intended?

David

[jsachs]

I fixed the problem with the initial setting of the Details control for the next maintenance release. I could not reproduce the radius slider scale problem, so if you have a way to produce the effect reliably, please let me know.

The detail control parameters are not saved in the .crv file which is also used with other transformations that do not know about the extra settings.

[davidh]

Jonathan,
the first results of the the testings have proved quite interesting.
First, the default position of the slider is in the middle of the scale, the number showing the value of 10. But when you click on the slider where it is, the value changes to 20 and after you reopen the dialog the slider is totally on the right of the scale, number showing 20 even though the real max value of the scale is 40. So it seems to be kind of scale and slider discordance, halving or doubling.

Next I have found:
If you move the slider up from the default value of 10 (20), the slider disappears when the dialog is closed and reopen.
You can put it back by a click on the scale, but if you click higher on the scale then was the previous value, the slider again disappears on the next dialog reopening.
But
If you click at a lower value then 10 (20) the slider remains when the dialog is reopen but appears at a different place (doubled value), though the number on the scale does show the value the slider was placed at.

To make the description more intellible:

place the slider to > 10 (20)
reopen the dialog
slider is not there

place the slider to < 10 (20) eg. 5
reopen
slider will be at the twice of that value on the scale = 10, but the value next to the Radius will show 5.

This was is not a thorough investigation, but I can simulate it anytime, so I think it might help with a clue. I tested it on a nootebook with Win XP. If necessary, tomorrow I can repeat it on 64 bit win 7, where I first came accross with this behavior. Or perhaps someone else might try to follow these steps on a different configuration to confirm or not.

David

[jsachs]

OK, thanks for the detailed report. I have fixed the factor of two error which was also causing the bad display since it was placing the slider handle beyond the end of the scale.

[davidh]

Would it make sense to include also the Detail Control new three parameters to the Reset command to set them to their defaults? Switching between No/Yes is useful for checking the effect, but there is no fast way to reset the Detail Control to "no effect" resp. the "default effect". Or maybe even better to add "Reset Only Detail Control" command?

David

[jsachs]

The Opt button is part of the Curve control which is shared by many other transformations and therefore knows nothing about the color space and detail parameters, so I would have to add a separate Opt button to reset all the transformation settings. This would probably be more confusing than helpful, but launching the brightness curve transformation while holding down the Shift key resets everything to the defaults, as it does for other transformations.

[davidh]

I tried to use the Detail Control to suppress unwanted detail while preserving some outlines (for other purpose than bluring noise or background) with the very similar results achievable also with the Precise Gausian Blur and Bilateral Sharpen. In fact it seems to use a similar process like generating the mean image and creating distinct bounderies, but it is faster than the latter two.
Even though it may not be possible with the Detail Control to achieve boundaries as smooth as with the Precise Gausian Blur (of the two only PGB is Precise), the Detail Control will offer interesting eventualities. Very useful. Jonathan and Kiril, thanks.

David

[jsachs]

The way it works is to split the input image into two components - a low pass (blurred image created as in bilateral sharpen) and a high pass image (computed by subtracting the low pass image from the input image). The low pass image captures the overall tonal variations while the high pass image captures the details. The brightness curve is applied to the low pass image and then the high pass image is added back in to create the output image. The idea is that the tonal variations can be applied to the input image while preserving its local contrast.

[davidh]

Jonathan,
thanks for the explanation of the principles behind. It makes clear my observed guesses based on the results I have been getting.
Thanks again for the upgraded or advanced Brightness Curve.

David