Manual White Balance in ELP Cameras - Possible?

[ma...@makr.zone]

Hi

I'm experimenting with some "green screen" vision to reliably recognize green 3D printed features agains any other objects (MaskHsv).

This works quite well if I switch on the automatic white balance of the camera, where a "natural" color look can be achieved.

Hower the automatic white balance obviously adapts to the scene. If a large area of a certain color is visible, the balance changes. For example if the green object that I want to recognize covers a large area, the neutral metal background becomes slightly magenta-tinted (magenta is the complementary color of green). That's actually good to distinguish the green object. Unfortuately the auto-balance takes time to adapt, so I must use a very large settle time to get acceptable images.

Therefore I'd like to switch off the automatic white balance setting (like I did with exposure) and choose a fixed manual value. However whatever I try I cannot achieve a natural look with the manual White Balance setting. Far from it actually, it's so bad I can forget reliable MaskHsv because the whole picture becomes greenish-yellowish or greenish-blueish. It never even comes close to magenta-tinted.

I'm also confused how white balance can be achieved at all with just one ruler. From a math standpoint, shouldn't there be three?

https://en.wikipedia.org/wiki/Color_balance#Mathematics_of_color_balance

I also tried to combine the Hue and White Balance rulers but I never achieved a good color look. Tests with OSB Studio resulted in the same limitation.

Is this a problem of the ELP camera? Or do other cams exhibit the same limitation?

Any tips?

Thanks,

_Mark

[ma...@makr.zone]

On Monday, May 13, 2019 at 11:07:32 PM UTC+2, fish wrote:

The manual white balance totally depends on the quality of light.I'm using some old osram duris e5 leds that give a good light at 4000 Kelvin at a high CRI (>85) t

 

Thanks, fish! I will look into that. What if you were to buy new LEDs? Any part numbers suggested? Can you share more about your lighting setup (layout, angle, diffuser, etc.)?

https://www.digikey.ch/products/de/optoelectronics/led-lighting-white/124?pv1615=3&sf=1&FV=ffec77b1%2C1f140000%2Cffe0007c

_Mark

[Marek T.]

What is the distance between the end of the tip and lens surface during alignment?

Do you low down the nozzle for aligning the part?

W dniu wtorek, 14 maja 2019 12:38:01 UTC+2 użytkownik fish napisał:

The duris e5 is seems to be still in production, but anything newer in this class would work.

It should be a led for professional lightning with CRI>85 and 4000k.

I am using only 8 pcs in serial at 24V - gives a strong cool white light.

Please look at attached images.

Especially for the crappy ELP modules i made a easy adustment gimbal to get rid of some nasty axis errors.

In the module i'm using now a very low distortion lens (yumiki 3.5mm from ali), but i'am not really happy with it.

[Allan Madsen]

Hi

Can you make bigger pic and maby a link to your stl files for the cam house??

tirsdag den 14. maj 2019 kl. 12.38.01 UTC+2 skrev fish:

The duris e5 is seems to be still in production, but anything newer in this class would work.

It should be a led for professional lightning with CRI>85 and 4000k.

I am using only 8 pcs in serial at 24V - gives a strong cool white light.

Please look at attached images.

Especially for the crappy ELP modules i made a easy adustment gimbal to get rid of some nasty axis errors.

In the module i'm using now a very low distortion lens (yumiki 3.5mm from ali), but i'am not really happy with it.

On Tuesday, May 14, 2019 at 8:59:34 AM UTC+2, ma...@makr.zone wrote:

[Allan Madsen]

Thanks :-)

tirsdag den 14. maj 2019 kl. 21.46.00 UTC+2 skrev fish:

@Allan: For bigger pictures i would point with mouse on image and press right button to view orignal size.

As stl files are much to big you have to import the step files to your cad and export stl for printing.

The drawing is a quick&dirty pre-version - it's far from perfect.

The inner gimbal spring housing should be on the outer gimbal.

Srew's for adjustment i use M3 (DIN7984).

Have fun.