Sola Technical's $70 acrylic scanning platform on Ponoko

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby vitorio » 08 Dec 2011, 17:18

After eagerly following the new model scanner development, I've decided to finish my tests with this scanner before proceeding with that one. So, let's buy a camera and build a blackout tent for it:

It's holiday season 2011, you can reasonably get 14MP and 16MP point-and-shoot compact and ultracompact cameras for around $100 or less. Neither this model nor the new kit require automated triggering, so this opens the question of other camera models besides the latest/most affordable Canon.

Imaging Resource (IR) has detailed reviews with image quality analyses for many low-end cameras, unlike DP Review, which seems to focus on high-end ones. Based on historical reviews on DP Review, Amazon user reviews and other forum users' use of CHDK, Canon, Sony and Panasonic cameras seem to be the best bets for reliable camera purchasing, rather than Nikon, Kodak or Fuji.

It also appears that cameras labeled as Bell & Howell, Vivitar and GE are similar model OEM cameras with incredibly poor lenses/sensors/false MP ratings (according to anecdotes on the internet) and should be avoided.

Panasonic Lumix camera lines seem to have similar sensors and features, and are differentiated by their housing and lenses: S series < FP series < FH series.

On all the IR reviews, I'm looking exclusively at sharpness, geometric distortion, chromatic aberration, resolution, ISO (detail at low ISO), performance and conclusion.

Based on that, these seem to be best bets for 16MP cameras:

I expect the equivalent 14MP models would also be good bets.

With the daintiness I suspect will be required handling the platen, picture-taking speed doesn't matter as much, so I've ordered the Sony because the low ISO performance seems to be a little better than the Canon's, and also to be contrary.

For testing performance in the scanner itself, a standardized chart was discussed here on the forums, but I don't understand why we wouldn't just use industry standard ones, similar to the tests IR does. Any chart we actually print at home is going to have a lot of variance in the visible detail and such because we all have different printers with different inks and different paper. I feel like we need to use ones produced by outside sources for consistency, even if it's just having a set of images in a print-on-demand book through Blurb or Lulu or wherever that have been color-matched with them.

IR's tests include an ISO standard chart for testing resolution. This is super interesting to me. The official PDF is ~100 (your unit of currency); in the US that's through ANSI for $142, but I think you really want to buy pre-printed paper charts for around the same price: http://www.precisionopticalimaging.com/ ... type=12233 or http://www.edmundoptics.com/products/di ... uctid=2287

That said, a replica is available here as a PDF, and I'll be printing this out and using it for basic tests: http://www.graphics.cornell.edu/~westin ... chart.html

If more people get to using it, maybe Scan Tailor and Book Scan Wizard could integrate code for doing slant-edge analysis to determine the resolution and help compare performance. Matlab code for that is here: http://www.i3a.org/resources/#iso

Color tests like this might also be nice: http://www.edmundoptics.com/products/di ... uctid=1815

Anyway, the Sony will be here tomorrow, and then I'll take pictures of the blackout tent with it.
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby vitorio » 17 Jan 2012, 17:33

Here's what a laser-printer-printed, cut-off-to-fit-8.5x11-paper, ISO 12233 resolution target looks like under the acrylic platen in ambient room light, taken with the Sony camera. The all-acrylic design means you can see all my debris around and behind the scanner, there's light reflecting from all over the place, and it's hard to tell exactly where from.

iso-ambient-light.jpg
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Some black fabric tells the story a little better:

black-fabric-ambient-light.jpg
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This is why you're supposed to use it in a pitch-black room with an overhead spot:

black-fabric-overhead-spot.jpg
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This was expected, so I built a 2' square PVC box and made blackout curtains by sticking black fabric to blackout cloth with hot glue. PVC pre-cut and connectors from Home Depot, fabric from Joann's:

blackout-tent.jpg
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A 18" tall PVC bracket was added on top of the box to mount an overhead incandescent light using a cheap clip-on work lamp, so it hung down a good six inches to perhaps 12" above the top of the box. For the top of the box, I tried using cotton batting (looked like clouds) and a white sheet to diffuse the light, but ended up just putting a higher-powered light to wash out the reflections. Reflections were coming from behind the camera and the left and right sides, all around the tower half, plus you can see me whenever I need to push the button (you can see my hand in the black triangle):

iso-blackout-overhead.jpg
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The 2'x2' box is pretty inefficient and makes it very difficult to move the platen to turn the page, so next I'll be making an L-shaped one, hanging the lamp at 24", increasing the wattage (it's 65w now), and adding a curtain between me and the shutter button.
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby daniel_reetz » 18 Jan 2012, 00:58

The black fabric trick is golden - nice investigation work.
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby vitorio » 23 Jan 2012, 01:45

Here's what I believe a pretty optimal frame for a blackout tent for this scanning platform is like:

pvc-blackout-frame-1.jpg


It's all pre-cut and threaded schedule 40 and 80 PVC from Lowes, with the diagonal ties being duct tape. It's 18" wide, the back (photo left) is 24" tall, 12" deep to the center, which is 48" tall, then 12" more to the front (photo right) which is 12" tall. The lower front makes it easy to lift the platen to turn the page, although it basically means I will have to position the book from the front, then walk around the other side to take the photo, then walk around to the front to turn the page, etc., every time. Apart from using a 24" lazy susan, I feel this is unavoidable if I want to be able to scan without the room being pitch black.

Turned a bit:

pvc-blackout-frame-2.jpg


The lamp clips onto the top of the 48" tall bit in the middle. I need to recut most of my blackout curtains, but the plan is to fully enclose the triangle made from the top of the 48" tall bit to the back (photo left) 24" tall bit (blue), hang a curtain across the front to cover hands when they're pressing the shutter (orange), mostly enclose the entire back 24" x 12" box, except for a bit at the top so you can see the screen of the camera (blue), and cover up the front (photo right, green), plus cover the table.

curtain-locations.jpeg


This photo shows most of that, with everything roughly in place, and it's pretty close to a dark room as far as avoiding ambient light. Once the curtains are in place I'll do a set of lighting tests, and then it's time to scan a book!

pretty-close.jpeg
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby vitorio » 12 Feb 2012, 06:06

I'm pretty sure I now know more about how best to use this scanner than its creator. Even working in a pitch-black room with only an overhead light source, it would have had problems.

I cut a new overhead curtain and aligned all of the rest of the blackout curtains using the camera viewfinder (middle row, 1.9x optical magnification), and using just ambient room light it looks like it's all working out well:

final-lighting-ambient-no-overhead.jpg
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But then you color-correct it and you can see the reflection of the tower and the facing platen!

final-lighting-ambient-no-overhead-corrected.jpg
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And using the proper overhead lamp doesn't wash it out, it makes it more obvious:

final-lighting-overhead.jpg
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You can see bits of the reflection in the black portions of the ISO test page, so it's not just in this worst-case test. The only way to avoid the reflections is to black out the entire tower and the facing platen!

But, when you do, you get a nice clean image:

final-lighting-covered-base-iso.jpg
final-lighting-covered-base-iso.jpg (107.92 KiB) Viewed 1850 times


So, that's it. I'm going to take some pictures of the curtain setup, and then (tediously, I expect) scan a book.
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby vitorio » 12 Feb 2012, 06:42

The final result needed fewer curtains around the rear tower than I originally expected, but added in the covering across the entire base. Here's the four views:

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WP_000016.jpg
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It's hard to tell what's going on inside there, but there's a curtain hanging in front of the camera, and then a covering across the entire cradle and up the tower, tucked in right against the camera. The hanging little bits of cloth on the left and right sides are because there were two little bits of glare coming off the PVC. Here's the interior:

WP_000019.jpg
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby vitorio » 12 Feb 2012, 06:53

Unfortunately, I'm going to have to continue work on either the new kit, or design something new, because this one is too small to properly scan in some of the more special books I have. I've attached two shots of a too-big typography manual, plus a smaller book I'll be trying. I haven't tried using Scan Tailor or Book Scan Wizard on them yet.
Attachments
DSC00178.JPG
DSC00179.JPG
DSC00181.JPG
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby goldo » 12 Feb 2012, 10:44

I assume that with that kit you always have to take the "v shape" fully appart, replace it at each page. There is no system to rise and put down the "v shape" (e.i with elastic)...
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby vitorio » 12 Feb 2012, 15:57

No, it's one big braced V-shaped piece all glued together. This post on the first page of the thread shows the V-shaped platen as separate from the cradle base (which I've now covered in blackout curtain), and you can look above that post for assembly photos.

With the addition of all the curtains, I now have to walk around to the front of the front of the platform to lift the platen up, turn the page, and set it back down, then walk around to the back to take the picture, and repeat.
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Postby goldo » 13 Feb 2012, 07:16

It is not obvious to see on the photo. Does the V-shaped slide up and down on the other plastic elements ?
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