qreator-discuss team mailing list archive

[David Planella <david.planella@xxxxxxxxxx>]

On Mon, Jun 10, 2013 at 10:43 PM, Stefan Schwarzburg <
stefan.schwarzburg@xxxxxxxxx> wrote:

> Hi
>
> On Mon, Jun 10, 2013 at 9:51 PM, David Planella <david.planella@xxxxxxxxxx
> > wrote:
>
>> On Mon, Jun 10, 2013 at 5:24 PM, Stefan Schwarzburg <
>> stefan.schwarzburg@xxxxxxxxx> wrote:
>>
>>> Hi David,
>>>
>>>  Thanks for the testing. From the size of the images and the picture, I
>>>> assume you took those from the desktop.
>>>>
>>>>
>>> True. I do not have any mobile that runs ubuntu :-(
>>>
>>>
>>
>> No worries. I cannot offer a phone, as I only got one myself, but let me
>> know if you have any snippet or branch you'd like me to test on a device.
>>
>>
>>> In my case, playing with exposure, white balance or brightness did not
>>>> make any difference when pictures were taken from the web cam. So we've got
>>>> two cases here: in my case images are too dark, and in your case images go
>>>> crazy. I think I share your conclusion that the camera settings *on the
>>>> desktop* are not very reliable at the moment.
>>>>
>>>>
>>> I'm actually not sure that they are always too dark on your phone as
>>> well. Maybe 5 out of 500 pictures were bright on my desktop, did you try
>>> that many on your phone? I have used automatic triggering, you can copy the
>>> code from my branch. Let it run for 15 minutes or so and then check your
>>> images for bright ones... :-)
>>>
>>>
>>
>> I still believe there is a difference between desktop and mobile, both at
>> the hardware level (e.g. my webcam does not support autofocus, whereas the
>> Nexus' one does) and at the software level (GStreamer-based plugin on the
>> desktop vs something else -I've not figured out yet what- on the Nexus).
>>
>> The automatic triggering is a really good idea. But eaven without doing
>> automatic triggering, for the ~30 or so pictures I've taken manually on the
>> desktop and on the device, the pictures are invariably always dark on the
>> desktop, and always ok on the device.
>>
>> If you've got the automatic triggering code somewhere, I'll give it a
>> shot on the device, but we should probably decouple it from Qreator and use
>> it as a separate test app.
>>
>>
> Sure, the code is here:
> lp:~stefan-schwarzburg/qreator/touch-scanner-automaticscan
>

Thanks!


>
>>
>>>> I'm not sure how we can correct that. In my case, it seemed that the
>>>> webcam ignored the settings, so it might be that either the hardware does
>>>> not support them, or that the camera plugin for the desktop is not passing
>>>> the parameters correctly. Which is weird, as the Qt camera plugin uses
>>>> GStreamer as a backend afaik, and Cheese, which also uses GStreamer, takes
>>>> pictures with the right brighthness.
>>>>
>>>
>>> Well, the viewfinder is always totally fine, one the still images are
>>> not.
>>> I also noted, that you do not use camera.searchAndLock() "Start
>>> focusing, exposure and white balance calculation." Maybe this mixes up
>>> exposure for viewfinder and still image...
>>> It would be great to directly get the image from the viewfinder instead
>>> of taking a picture...
>>>
>>
>> Yeah, I'm not sure if it's possible, though. In any case, in the (I must
>> admit) very limited photography knowledge I have, I always assumed that the
>> exposure is longer on the video preview, which is why the pictures always
>> look ok on the preview. Now this might be a totally wrong assumption,
>> though...
>>
>> I'll give a shot at searchAndLock(), but I'm a bit disappointed to see
>> that at least on the desktop the Camera component is not as plug-and-play
>> as the documentation leads to believe....
>>
>>
>>>
>>>
>>>>
>>>> In my testing on a device, the white balance/brightness/exposure seem
>>>> correct, so this issue apparently only affects the desktop version.
>>>>
>>>
>>> Well, if your images are too dark, then exposure is not ok!
>>>
>>>
>>
>> Right, but the point is that images are never dark on the device, only on
>> the desktop.
>>
>>
>>>
>>>> Another issue that I've now got more insight on is the delay in
>>>> decoding from a device. It takes about 15-20 seconds to decode a QR code,
>>>> but in the limited testing that I've done it seems to work every time,
>>>> which is really good.
>>>>
>>>
>>> For me it worked everytime the brightness was ok.
>>>
>>>
>>
>> Yeah, on the desktop, if I point a bright light at the QR code, the
>> decoding takes about 1s, which is optimal. On the device, it takes these
>> 15-20 seconds, which I assume to be due to the additional time it takes to
>> process a higher resolution picture.
>>
>> On the desktop the resolution of my captures is 640x480
>> On the device I'll have to check when it's finished charging, but I'm
>> pretty certain it's a very high resolution.
>>
>> Which resolution do you have on your webcam?
>>
>
> Format Video Capture:
>         Width/Height  : 640/480
>         Pixel Format  : 'YUYV'
>         Field         : None
>         Bytes per Line: 1280
>         Size Image    : 614400
>         Colorspace    : SRGB
>
>

Yeah, similar to my cam. Resolution on the device's cam is 3264x1836px.


>
>>
>>>> I believe what might be happening here is that it takes quite a lot of
>>>> memory or processing power to scan and decode the images with higher
>>>> resolution from the device's camera (on my desktop it takes about 1 second
>>>> to decode the webcam's 640x480 images).
>>>>
>>>
>>> You could try to move a desktop-webcam picture and let it scan on the
>>> mobile (hardcoded), just to see the time difference. But sure, higher
>>> resolution should increase the time drastically.
>>>
>>>
>>
>> Yeah, that's a good idea. I've also thought of implementing a very rough
>> shot of your image-loading feature and get the desktop load a capture from
>> the device. I think I will try that next.
>>
>> I really want to nail this one down. We can work the workflow in Balsamiq
>> in parallell, but I'd really like to get the basics of capturing and
>> decoding right and solid.
>>
>
> Sure, anything I should work on  so that we do not work on the same things?
>
>

I think whatever you find more interesting or more fun :)

In any case, I've got a few suggestions if you'd be interested in any of
them. I think if I can spend a couple of hours on it tonight, I'll try to
work on getting the C++ plugin to work on a device, make it more
user-friendly and get the automated scanning feature to work.

Here are the suggestions:

- Fixing camera exposure on the desktop
- Video output size (I'm not sure how to best scale the video output,
especially on desktop when resizing the window. I think it should be
anchored to the top and grow to fill the window's width while keeping the
aspect ratio, but I'm not too sure yet - any ideas?).
- Stopping cam when switching tabs, when the decoding dialog is shown, and
when app does not have the focus (the latter is already implemented in the
camera-app in Ubuntu)
- Anything else that makes the scan view more usable :)

Cheers,
David.


> Cheers,
> Stefan
>
>
>>
>>>
>>>> I'll try to benchmark if the C++ plugin can do this much faster, but in
>>>> any case, a couple of measures I can think of are:
>>>>
>>>> ~ Reduce the resolution of the captured image
>>>> ~ Crop the captured image to the QR code window before sending it to
>>>> the decoding library functions
>>>>
>>>>
>>>> In terms of the QR code window, I've started adding some preliminary
>>>> code to show where the QR code should be positioned in the picture to be
>>>> scanned, but it's not yet functional (i.e. the window is shown, but it does
>>>> not do anything).
>>>>
>>>>
>>> The new window looks very nice!
>>> And I have seen that you added the dialogs, with an even better "dynamc
>>> text" mechanism :-) Nice!
>>>
>>>
>> Not sure if better, just an alternative :). I've now answered the
>> question on Ask Ubuntu with the solution. Thanks for your answer! :)
>>
>> Cheers,
>> David.
>>
>>
>>> Cheers,
>>> Stefan
>>>
>>>
>>>> I've updated the code on the scanner branch:
>>>> lp:~dpm/qreator/touch-scanner
>>>>
>>>> Cheers,
>>>> David.
>>>>
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>>>>
>>>
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>>>
>>
>
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