Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Do we actually need portable cameras ?

Everything camera related. Includes triggers, batteries, power supplies, flatbeds and sheet-feeding scanners, too.
Stevo
Posts: 10
Joined: 10 Sep 2012, 12:51
Number of books owned: 0
Country: Aus

Re: Do we actually need portable cameras ?

Post by Stevo » 11 Sep 2012, 08:25

reece.arnott wrote:The problem is not the sensor, it is the streaming video component. Standard HD streaming of 1080p at 24 frames a second, assuming a 16:9 aspect ratio,give a frame resolution of 1920x1080 (the approx 2MP you are getting) giving 48MB/s or 384Mb/s (thats B=bytes vs. b=bits). USB 2.0 maxs out at 480 Mb/s so to get higher resolution per frame, you need to take the framerate down (until USB 3 takes off and we can push 5 Gigabits per second down the USB line).

Edit: technically 1 pixel could be equal to 3 or 4 bytes depending on format but with good compression, a good rule of thumb is that 1 pixel=1 byte.

There may be options to decrease the framerate and increase the resolution in some software but not in others as I can get higher in guvcview - it does 15 frames a second at 2048x1536 as well as 10 fps at full 2592x1944 (although presumably because of the max resolution of my monitor or some weird issue in guvcview it screwed up showing the largest).

Edit: The partial output of a command line query I ran to get valid MJPEG resolution/framerate options (1/30 means 30 frames every second 2/15 means 15 frames every 2 seconds etc.) as reported by my Logitech C910.

{ discrete: width = 1280, height = 720 }
Time interval between frame: 1/30, 1/24, 1/20, 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1392, height = 768 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1504, height = 832 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1600, height = 896 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1280, height = 960 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1712, height = 960 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1792, height = 1008 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1920, height = 1080 }
Time interval between frame: 1/30, 1/24, 1/20, 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 1600, height = 1200 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 2048, height = 1536 }
Time interval between frame: 1/15, 1/10, 2/15, 1/5,
{ discrete: width = 2592, height = 1944 }
Time interval between frame: 1/10, 2/15, 1/5,
Yes, sorry to crash into the thread, I understand this is the official thread for these things.

Astro camera software systems:
This is the sort of thing to look at. Years ago I was looking into USB webcams for video, been over to elphel too. I did find a group or two doing direct camera control, and uncompressed output (though min compression at highest resolution might be better). However, the astronomy people also do this, and it is worth che king out their software.

Android and IPhone:
There are a few packages that add better camera features to these, maybe they also have trigger and high quality/uncompressed modes.

The higher end brands should have 5mp+ native quality webcams by now. I think I saw them last year or so. These should use similar chips to the cheap full HD camcorders you see for under $200.

Some of the cheap under $200 fullhd video cameras have webcam mode, but ussually low res video, but I have never tried stills capture. I have an old 14mp Sanyo Gs20. I think there might be camera control features through USB, I might have to try it through a couple of programs and see if paperport 12 has any controls.

USB3 point grey 4k 21fps (8mp+) machine vision:

Some of these machine visions camera companies have excellent software, and for handling true 3d mapping of objects ( can't remember if this was point grey ir another I was checking out back them). However, you can probably get a machine vision camera that does low frame rate still at least hundreds. The issue with webcams is you generally are getting low quality cheap, without good on sensor pixel pad structure filters (particularly complimentary color filters instead of Bayer). With machine vision, you should be looking at higher quality, though supreme quality does not matter in all cases.

However, you can get some sensor companie's development camera modules with USB etc at a reasonable price . I forget the name of the company that sells them, but they dealt with omnivision sensors.


Display link/thunderbolt can send video directly into the computers memory with minimal computer processor overhead (USB sucks and requires special drivers to get even close to 50MB/s, USB 3 is much better but still has issues, display link is better). If you ever see thunderbolt cameras come out they will be worth exploring for high speed scanning).
Last edited by Stevo on 11 Sep 2012, 17:54, edited 1 time in total.

Stevo
Posts: 10
Joined: 10 Sep 2012, 12:51
Number of books owned: 0
Country: Aus

Re: Do we actually need portable cameras ?

Post by Stevo » 11 Sep 2012, 08:43

I forgot, I remember some of the sports action cams having a trigger option, and they use similar 5mp etc sensors as the low cost video cameras, Gopro latest, uses a fullhdp24 36mb/s h264 firmware update. For high speed that is as good as you will get in a video mode on a cheap camera for now (suspect that a 4k camera some day). But JVC, others, and the chipset makers of those under $200 cameras can rip uncompressed frames off sensor in over 8mp at 30-60fps, even if not implemented. If you want to know about quality video capture off the hdmi port of various cameras (most give a dumbed down version), contact me. I suspect we might have a 4k capture option sometime.

dtic
Posts: 461
Joined: 06 Mar 2010, 18:03

Re: Do we actually need portable cameras ?

Post by dtic » 11 Sep 2012, 12:40

It might be worth mentioning to anyone new to this thread that use of portable cameras has only become easier during the last year. A few highlights:

- CHDK now supports many more cameras including newer ones that shoot faster, have more internal memory and higher image resolution.
- CHDK now supports LiveView on a usb connected computer
- you don't need custom remote trigger hardware for CHDK. Any computer with usb ports is sufficient to trigger shots. You can also script the cameras to shoot automatically at certain time intervals.
- CHDK lets you lock the camera focus so you don't have to wait for a refocus for each shot
- used compact cameras with CHDK can be bought at very low cost (look for A490 A495 or A800 ).
- many powershots are powered by regular AA batteries. Use rechargeable batteries and the cost is minimal. You can take hundreds of photos before you need to switch batteries.

Maybe something better than portable cameras will come along but they're pretty good for the time being.

LA2
Posts: 19
Joined: 01 Feb 2012, 16:43
Number of books owned: 1000
Country: Sweden
Location: Linköping, Sweden

Re: Do we actually need portable cameras ?

Post by LA2 » 08 Dec 2012, 14:30

Someone mentioned the Logitech C910, which is a $100 webcam that takes 10 megapixel still images. I learned that there is now also a Logitech C920, which at $70 takes 15 megapixel still images. The problem with all webcams, however, is that they have a fixed optical zoom, at quite a wide angle. To get those pixels covering the book page, you need to be very close to the book (~1 ft). This forces you to use a design similar to what Reece Arnott uses, or the Ion Audio Booksaver. These designs make it impossible to avoid glare from light sources, no matter where the lights are placed. To avoid glare, you need a narrow zoom and a good distance (~3 ft) between book and camera.

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