White balance / other settings for photographing books

[Photo Golf]

My wife is currently starting her PhD, and as part of that has to read multiple books.

She regularly has to photocopy / scan books from the library, which takes an inordinate amount of time.

I have found using a tripod, some lights, my Canon 5D MkII and Lightroom, I can very quickly photograph each page, crop them and turn them into a pdf for her - far faster than she can photocopy. The design of our "home scanner" is basically like the basic model discussed on this site DIY Book Scanning

The problem I have is that no matter what I do, all the photos come out with a light gray background. From the research I have done on the web, it appears that photographing pages of books "tricks" the camera in that it reads the page as being a mix of black and white that equals a light gray, and it exposes / sets white balance on this basis.

I've tried:

. adjusting the white balance (both in the camera, and in Lightroom - I'm shooting raw)
. adjusting the exposure (up to 1.5 full stops) - this helps a little, but doesn't solve it, and the higher you go, the more you blow out the text
. adjusting various levels in lightroom - the most effective was to move to grayscale, and then changing the lights and darks in the tone curve, but firstly this won't work for colour books, and it doesn't get the best result
. using flash
. changing the bulbs in the lights. I am using two "desk lamps" with 75W 5000 kelvin daylight bulbs

Suggestions ? Thoughts on best settings / technique ?

Thanks in advance

[Chip]

Interesting. Would you mind posting an example or 2 so that we can see what you're talking about?

[Benji]

If those books are copyrighted what you are doing is illegal.

Benji

[Chip]

Originally Posted by Benji

If those books are copyrighted what you are doing is illegal.

Benji

I'm not so sure, Benji. My understanding is that as long as it's done for personal use, it's considered "fair use" and permissible.

If not, then how is taking a photo of pages from a book any different than making a photocopy of those same pages? Or are you saying that making a photocopy is illegal, too?

I know Google is catching flack for scanning books and putting them online, but to me, that doesn't come close to meeting the fair use test.

[kirbinster]

There is an exception in copyright laws for educational use.

Why not just use the whitebalance dropper in lightroom to adjust the WB on one shot and then sycronize all your shots to that one. Other option would be to set a custom white balance for the camera before you do all your shooting.

[LoveDSLR]

Try custom WB and set exposure against 18% gray card (~incident metering) in manual mode.

[Photo Golf]

For those concerned about legality, my wife is fully aware of the rules (and I am not). As others have commented, there are various rules around photocopying books for research use including nature of use, how much of the book you can copy, etc - she sticks to those rules.

I'll attach some examples in the next few threads.

[Photo Golf]

All of these were shot under the same conditions:

. Canon 5DMkII
. Camera Raw images
. ISO 100
. AV setting, F20 (I have tried various other F stops - it doesn't change the result - this exposure picked to ensure no focussing issues
. Varying speeds (will comment on each)
. White balance set to 5000k
. Spot metering on centre of book (I have tried with other metering modes, but this seemed the best to ensure metering was based on book, and not picking up any background from outside the book area)
. On a tripod
. Lighting - in a study, in daylight with blinds closed and two desk lamps with 5000 kelvin 75W lamps (I have tried in a variety of light conditions including daylight - no significant change, although the lights seem to get me a better result)

The only post processing I have done on them is in Lightroom to:

. Crop to the size of the page
. Reset the white balance using the dropper tool

First photo below was taken at the light settings as set by the camera based on above (1/13th)

[Photo Golf]

Following photos taken with above settings, but upping the exposure.

(Note the quality on all of these of the text is not great - that of course reflects the small jpg size needed to upload to this website. The original images are relatively easy to read the text if you can live with the gray background).

Next one at 1/5th. Gray effect is not as bad, but still a problem



and now one at 1/3rd of a second



as can be seen here, background is improving to closer to white, but still not white, but text is being blown out.

Lastly, here's one that has been converted to grayscale



These photos are all Black & White text, of course if I were to photo colour, the blow out gets worse after a few F stops. Of course for colour pages with photos etc, the result is horrible.

Any thoughts and suggestions people have would be much appreciated.

[ttosifa]

Assuming the page is white (except for the text), you have an exposure issue. This can be seen by looking at the histogram. The picture is greatly underexposed.

You say you can't increase the exposure without "blowing out the text." I don't know what you mean exactly. There are two potential causes.

One (very likely) is that your lighting is wrong. Assuming the text is black, blowing out the text wouldn't seem very likely. The paper might be partially reflective so that your light is bouncing off the page. Or the ink itself could be reflective. This will obscure the text, but it is not really blowing it out -- in the oft-used language of photography, the reflections are causing hot spots.

You'll either need to experiment with your lights so that you don't get reflections, or get the book "Light: Science and Magic" that will help to explain the angles of reflection. I recall they do have examples on photographing art and such that would be relevant to your problem.

Another potential issue in the example you posted is that light is hitting the camera lens, which reduces contrast. The light could be reflecting off the page so that as you expose more you lose even more contrast.

A properly exposed photograph should give you a white background. A properly lit photograph should additionally make the text readable.