Glare Reduction Techniques

[univurshul]

Lighting plays a vital role in book scanning. There's a great online resource that focuses solely on the properties of lighting: http://www.lrc.rpi.edu/

There's an interesting section on glare as well: http://www.lrc.rpi.edu/programs/nlpip/l ... rolled.asp

As I go through testing lights and glare issues, I'll be drawing what useful information I can from LRC and their data that can help with hardware construction/mods on our own DIY devices.

EDITED 7/24/10: I've looked at addressing some glare issues by focusing on hardware factors and some interesting tweaks. I invite anyone with ideas to share here; links, other examples, material suggestions, etc.

I'm going to start with lighting...
Lighting: Addressing how the lamp position casts light over the platen.

With a dual halogen system, I've discovered that glare on the platen is significantly reduced when both lamps are re-positioned from a side-by-side wide stance to a more central position that point directly into the "V", bottom of the platen.

Distance from bottom "V" of platen to the surface of the halogens is 33". 2x150watts.

One reason why this is better in my circumstance is that I believe that these halogens are wide angle bulbs at 160 degrees. If you're halogen's bulb angles are narrow, you still may benefit from a wider, spaced setting.

[univurshul]

...which brings me to another step of addressing an eco & glare-deterent lighting solution for my next rig:


If the platen prefers a rectangle light shape, I say use a commercial street light LED bulb. 28 watts, E40 socket; better than a 300-watt inferno halogen set. Color-balance? --good question, we'll see...

[spamsickle]

Many cameras will let you set a custom white balance, which should give you good results with any light source.

My browser doesn't do TIFF, so I don't know what's in the second set of pictures.

[univurshul]

LED pics re-posted in jpeg format

[spamsickle]

Thanks. I know I can dig through the cache, but I'm lazy!

Heh, a 30-watt light with its own fan. I remember Dan said LEDs were hot, but that's still unexpected.

[univurshul]

80,000 hour life. 2,100 lumens

This model here uses a heat-sink:

[Gaaren-gaargle]

The lamp looks neat!
How about trying using a diffuser, this will make the light spread more evenly across the page. This will reduce the light intensity a bit, but you can probably have your light source closer to the book.

[univurshul]

How about trying using a diffuser, this will make the light spread more evenly across the page. This will reduce the light intensity a bit, but you can probably have your light source closer to the book.

The only diffusion I've tried is by scanning under daylight next to a south-facing window. If you've seen something online, send me the link; I've never worked with a hardware diffuser. When it comes to 'intensity' as you put it, that sounds like you're referring to lumens. And if you're going to reduce lumens to avoid glare, you might as well buy a lower wattage bulb.

[Gaaren-gaargle]

@univurshul: I'm refering to lux. I may have expressed myself a bit incorrectly: what I meant was that if the light has to move through a diffusor, some of the light will be reflected back and this will make less photons land on the page. However the diffusor will make the light more scattered("soft") vs a uniformly defined spot light, and you will therefore probably be able to move the light-source nearer to compensate for the loss of lux (when you shorten the distance by 1/2 you'll, the lux will increase 1/4).

[univurshul]

@univurshul: I'm refering to lux...However the diffusor will make the light more scattered("soft") vs a uniformly defined spot light, and you will therefore probably be able to move the light-source nearer to compensate for the loss of lux (when you shorten the distance by 1/2 you'll, the lux will increase 1/4).

A diffuser like this example?: http://www.malcolite.com/index.php?id=9,5,0,0,1,0
If there's something else that you're trying to describe, please provide a reference or URL link.

This reminds me of another LED panel light, my guess is that the cover acts as a diffuser, however anything that lowers transmission, forcing light to pass through a material will reduce lumens.

'lux" is foreign to me. I need to to study light properties further before I start implementing obstruction via diffusion, which in turn, could force me to buy brighter lights, etc. The cycle will feed on itself.


Here's another post about diffusion: http://www.diybookscanner.org/forum/vie ... p?f=4&t=54