[digiKam-users] Hot pixel tool

[Lutz Epperlein-2]

Hi,

I did some trials with astro photography using a long exposure time
(30 seconds). This lead to a lot of hot pixels in the image. So I
thought this could be a good opportunity to use the hot pixel tool of
the image editor. But I'm a bit disappointed.

The loaded black frame shows nearly 400 hot pixels! Visual
investigation shows about 20-40 hot pixels, I guess. The hot pixels are
shown only in upper part of the image. But there are hot pixels in the
lower part of the image definitely. Are I doing something wrong?

Here is a screenshot of the tool:
<https://epperleinberlin.name/owncloud/index.php/s/qhgq8zhryHmQ1pA>

This is with Digikam 5.9.0 on openSUSE Leap 42.3

Regards
Lutz


--
Lutz Epperlein
GPG-Fingerabdruck:
5529 3F59 1989 E5DF 0F91  3AE4 9E7E ABCD 777C FD9F

[Gilles Caulier-4]

Ownclound said that file is not visible... Link is broken ?

Note : the editor preview mode can be changed with button on the bottom right. You are certainly in wrong preview mode to see only a part of preview over the canvas.

Gilles Caulier

2018-08-13 22:25 GMT+02:00 Lutz Epperlein <[hidden email]>:

Hi,

I did some trials with astro photography using a long exposure time
(30 seconds). This lead to a lot of hot pixels in the image. So I
thought this could be a good opportunity to use the hot pixel tool of
the image editor. But I'm a bit disappointed.

The loaded black frame shows nearly 400 hot pixels! Visual
investigation shows about 20-40 hot pixels, I guess. The hot pixels are
shown only in upper part of the image. But there are hot pixels in the
lower part of the image definitely. Are I doing something wrong?

Here is a screenshot of the tool:
<https://epperleinberlin.name/owncloud/index.php/s/qhgq8zhryHmQ1pA>

This is with Digikam 5.9.0 on openSUSE Leap 42.3

Regards
Lutz


--
Lutz Epperlein
GPG-Fingerabdruck:
5529 3F59 1989 E5DF 0F91  3AE4 9E7E ABCD 777C FD9F

[Lutz Epperlein-2]

Sorry, hopefully this link works:
<https://epperleinberlin.name/owncloud/index.php/s/cUuQQE5YazMNP1L>

> Note : the editor preview mode can be changed with button on the
> bottom right. You are certainly in wrong preview mode to see only a
> part of preview over the canvas.

I don't think so. The view is independent of the choosen preview mode.
And if I apply the settings to image, it looks like it is applied to the
upper part of the image only.

Thanks for the quick answer.

Regards
Lutz

--
Lutz Epperlein
GPG-Fingerabdruck:
5529 3F59 1989 E5DF 0F91  3AE4 9E7E ABCD 777C FD9F

[Lutz Epperlein-2]

Sorry again, I got some serious problems with the owncloud, so I
uploaded the screenshot now here:

<https://epperleinberlin.name/piwigo/picture.php?/1419/category/46>

Am Tue, 14 Aug 2018 20:27:11 +0200
schrieb Lutz Epperlein <[hidden email]>:

> Sorry, hopefully this link works:
> <https://epperleinberlin.name/owncloud/index.php/s/cUuQQE5YazMNP1L>
>
> > Note : the editor preview mode can be changed with button on the
> > bottom right. You are certainly in wrong preview mode to see only a
> > part of preview over the canvas.  
>
> I don't think so. The view is independent of the choosen preview mode.
> And if I apply the settings to image, it looks like it is applied to
> the upper part of the image only.
>
> Thanks for the quick answer.
>
> Regards
> Lutz
>

[Gilles Caulier-4]

Can you share the image to process and the hot pixel one. I would to try in my computer.

Gilles Caulier

2018-08-14 21:59 GMT+02:00 Lutz Epperlein <[hidden email]>:

Sorry again, I got some serious problems with the owncloud, so I
uploaded the screenshot now here:

<https://epperleinberlin.name/piwigo/picture.php?/1419/category/46>

Am Tue, 14 Aug 2018 20:27:11 +0200
schrieb Lutz Epperlein <[hidden email]>:

> Sorry, hopefully this link works:
> <https://epperleinberlin.name/owncloud/index.php/s/cUuQQE5YazMNP1L>
>
> > Note : the editor preview mode can be changed with button on the
> > bottom right. You are certainly in wrong preview mode to see only a
> > part of preview over the canvas. 
>
> I don't think so. The view is independent of the choosen preview mode.
> And if I apply the settings to image, it looks like it is applied to
> the upper part of the image only.
>
> Thanks for the quick answer.
>
> Regards
> Lutz
>

[Lutz Epperlein-2]

You can download both files from my piwigo:
<https://epperleinberlin.name/piwigo/index.php?/category/46>

Thanks
Lutz

Am Tue, 14 Aug 2018 23:06:21 +0200
schrieb Gilles Caulier <[hidden email]>:

> Can you share the image to process and the hot pixel one. I would to
> try in my computer.

[Maik Qualmann]

The image exceeds const int maxHotPixels = 1000, so it will be canceled.

From code:

// If you accidentally open a normal image for a black frame, the tool and
host application will
// freeze due to heavy calculation.
// We should stop at a certain amount of hot pixels, to avoid the freeze.
// 1000 of total hot pixels should be good enough for a trigger. Images with
such an amount of hot pixels should
// be considered as messed up anyway.

Maik

Am Dienstag, 14. August 2018, 23:21:22 CEST schrieb Lutz Epperlein:

> You can download both files from my piwigo:
> <https://epperleinberlin.name/piwigo/index.php?/category/46>
>
> Thanks
> Lutz
>
> Am Tue, 14 Aug 2018 23:06:21 +0200
>
> schrieb Gilles Caulier <[hidden email]>:
> > Can you share the image to process and the hot pixel one. I would to
> > try in my computer.

[Maik Qualmann]

The black image has 2701 hot pixels ...
I notice no speed problem if we maybe increase the value to 5000?

Maik

Am Dienstag, 14. August 2018, 23:33:43 CEST schrieben Sie:

> The image exceeds const int maxHotPixels = 1000, so it will be canceled.
>
> From code:
>
> // If you accidentally open a normal image for a black frame, the tool and
> host application will
> // freeze due to heavy calculation.
> // We should stop at a certain amount of hot pixels, to avoid the freeze.
> // 1000 of total hot pixels should be good enough for a trigger. Images with
> such an amount of hot pixels should
> // be considered as messed up anyway.
>
> Maik
>
> Am Dienstag, 14. August 2018, 23:21:22 CEST schrieb Lutz Epperlein:
> > You can download both files from my piwigo:
> > <https://epperleinberlin.name/piwigo/index.php?/category/46>
> >
> > Thanks
> > Lutz
> >
> > Am Tue, 14 Aug 2018 23:06:21 +0200
> >
> > schrieb Gilles Caulier <[hidden email]>:
> > > Can you share the image to process and the hot pixel one. I would to
> > > try in my computer.

[Gilles Caulier-4]

As the image parsing is multi-threaded (or at least must use one separated thread), this must be acceptable.

I don't remember if i patch this code to use multi-core in the past. If it's not the case, it's easy to do, as i do with other editor tools.

We can limit the max number of hot pixel with a setting in tool view.

Gilles Caulier

2018-08-14 23:39 GMT+02:00 Maik Qualmann <[hidden email]>:

The black image has 2701 hot pixels ...
I notice no speed problem if we maybe increase the value to 5000?

Maik

Am Dienstag, 14. August 2018, 23:33:43 CEST schrieben Sie:

> The image exceeds const int maxHotPixels = 1000, so it will be canceled.
>
> From code:
>
> // If you accidentally open a normal image for a black frame, the tool and
> host application will
> // freeze due to heavy calculation.
> // We should stop at a certain amount of hot pixels, to avoid the freeze.
> // 1000 of total hot pixels should be good enough for a trigger. Images with
> such an amount of hot pixels should
> // be considered as messed up anyway.
>
> Maik
>
> Am Dienstag, 14. August 2018, 23:21:22 CEST schrieb Lutz Epperlein:
> > You can download both files from my piwigo:
> > <https://epperleinberlin.name/piwigo/index.php?/category/46>
> >
> > Thanks
> > Lutz
> >
> > Am Tue, 14 Aug 2018 23:06:21 +0200
> >
> > schrieb Gilles Caulier <[hidden email]>:
> > > Can you share the image to process and the hot pixel one. I would to
> > > try in my computer.