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

Converting Color/Grayscale Text Scans to Black & White

Share your process here - how to build something, scan something, or use something.
russca
Posts: 53
Joined: 04 Mar 2014, 00:53
Number of books owned: 0
Country: ____

Converting Color/Grayscale Text Scans to Black & White

Post by russca » 04 Sep 2015, 15:33

I made a video tutorial on how to convert Color/Grayscale Text Image Scans to Black & White in Photoshop. This tutorial can also be used for despeckling scanned pages using blending modes. This process can be automated per book project by recording steps in Actions and executing them in Automate/Batch in the File menu. Hope it helps in your scanning endeavors.

https://www.youtube.com/watch?v=xhWH6YQazhw



Comparison:
black-and-white-conversion.gif

BruceG
Posts: 67
Joined: 14 May 2014, 23:17
Number of books owned: 500
Country: Australia

Re: Converting Color/Grayscale Text Scans to Black & White

Post by BruceG » 06 Sep 2015, 02:37

russca
Thanks for the tutorial. I managed to to get Photoshop Elements 8 to do the same thing except automatic batch mode.
I have a number of books from Internet Archive which often come yellow tint/hue page. I can remove the yellow on text pages (with InFix, a pdf editor) but it has been a problem to remove it in photos. Up to now impossible. So thanks. As I OCR it looks strange with the photos with a yellow tint/hue.
Thanks again.

qv_
Posts: 39
Joined: 01 Jul 2014, 17:33
E-book readers owned: iRiver
Number of books owned: 1000
Country: Sweden
Location: Sweden, Södermanland

Re: Converting Color/Grayscale Text Scans to Black & White

Post by qv_ » 03 Oct 2015, 16:00

When I read books I find it more comfort to read a text in grayscale vs black & white.

So I am heading for better grayscale to get even more "easy read" books.

/Jan

russca
Posts: 53
Joined: 04 Mar 2014, 00:53
Number of books owned: 0
Country: ____

Re: Converting Color/Grayscale Text Scans to Black & White

Post by russca » 11 Oct 2015, 08:49

For good measure, here are the original color and grayscale scans:
color-grayscale-scans.jpg
color-grayscale-scans.jpg (251.81 KiB) Viewed 12903 times

russca
Posts: 53
Joined: 04 Mar 2014, 00:53
Number of books owned: 0
Country: ____

Re: Converting Color/Grayscale Text Scans to Black & White

Post by russca » 11 Oct 2015, 09:03

BruceG wrote:I managed to to get Photoshop Elements 8 to do the same thing except automatic batch mode.
I have a number of books from Internet Archive which often come yellow tint/hue page. I can remove the yellow on text pages (with InFix, a pdf editor) but it has been a problem to remove it in photos. Up to now impossible. So thanks. As I OCR it looks strange with the photos with a yellow tint/hue.
Glad the tutorial was of help to you. Without automation this process is too much of a pain though. Are you using Windows XP or later?
qv_ wrote:When I read books I find it more comfort to read a text in grayscale vs black & white.
So I am heading for better grayscale to get even more "easy read" books.
It's fine if you are planning to read books only in a digital format. There are many people who prefer paper books to digital. I am one of them. For me printing in grayscale is impractical and environmentally irresponsible compared to black and white. In some cases paper books are the only way possible, such as textbooks and materials for school children in the remote areas of developing countries. In places like these electricity might be rationed or even not available due to poor infrastructure.

qv_
Posts: 39
Joined: 01 Jul 2014, 17:33
E-book readers owned: iRiver
Number of books owned: 1000
Country: Sweden
Location: Sweden, Södermanland

Re: Converting Color/Grayscale Text Scans to Black & White

Post by qv_ » 11 Oct 2015, 15:15

I also prefer to read paperbooks but the books I scan is workshops manuals for old cars and they will be read in a computer when I need them.
But the amount of pages (several tusens) make a need for "easy reading" and reading when scroling the text. There I see that grayscale is mutch more comfortable to read.
But if you scan the text and only planning to use the scan for printing things may be different.

I like gray scale = esay to read
I need 300 dpi = schematics use smal fonts and photos of work flow
I need color = hydralic flow

so in the end (for me) is color/grayscale 300DPI a minimum to get use of all the hours it takes to scan.

If you adjust the white balance on the camera you might get som of the gray background white and don´t have to convert so much.

/Jan

cday
Posts: 226
Joined: 19 Mar 2013, 14:55
Number of books owned: 0
Country: UK

Re: Converting Color/Grayscale Text Scans to Black & White

Post by cday » 12 Oct 2015, 08:05

qv_ wrote:[on a computer screen] ... I see that grayscale is much more comfortable to read.
But if you scan the text and only planning to use the scan for printing things may be different.
Grayscale text is easier to read on a screen because the edges of the characters can be smoothed (anti-aliased) using intermediate shades of gray.

Text to be displayed as black and white (1-bit colour depth) needs to be scanned at a higher DPI in order to display well, which of course significantly increases scan time.

But pages scanned at 300dpi for display as grayscale can still be enhanced to have a near-white background if suitable image processing settings are used, or better if a flatbed scanner is being used, if the optimum scanner settings are determined before starting a series of scans. Time spent in familiarisation with the available scanning options is usually time well spent.

russca
Posts: 53
Joined: 04 Mar 2014, 00:53
Number of books owned: 0
Country: ____

Re: Converting Color/Grayscale Text Scans to Black & White

Post by russca » 13 Oct 2015, 09:38

cday wrote:Time spent in familiarisation with the available scanning options is usually time well spent.
Additionally, I examine each book before proceeding with scanning and select appropriate steps to maximize quality of scans. And then I test till I get acceptable results. One of the steps is choosing the right scanner for the job. Currently, I have Plustek Opticbook 3800, Fujitsu ScanSnap S1500, Canon 9000F flatbed and a custom-made aluminum V-shaped DSLR camera scanner that can scan up to two A2-sized pages.
cday wrote:Grayscale text is easier to read on a screen because the edges of the characters can be smoothed (anti-aliased) using intermediate shades of gray.
That's the reason why the second method (Blending modes) in my tutorial gives better results. There are many shades between black and white in the saved file. Think of 256 color table used for grayscale gif image saving.
color-table-gif.gif
color-table-gif.gif (109.8 KiB) Viewed 12839 times

duerig
Posts: 364
Joined: 01 Jun 2014, 17:04
Number of books owned: 1000
Country: United States of America

Re: Converting Color/Grayscale Text Scans to Black & White

Post by duerig » 13 Oct 2015, 11:13

When I first read this before, I didn't realize that blending modes was actually a grayscale picture. One of the things I've been looking for was a way to sharpen grayscale images of a page. Doing an actual sharpen operation or tweaking contrast/brightness seemed too inconsistent. I like your blend modes. And I have discovered that you can do the exact same thing with imagemagick to automate the process.

One other tweak is that after running your Screen/Multiply, you can normalize the image so that it spreads the shades all the way between white and black. This makes the text a bit darker and the background a bit lighter.

-D

russca
Posts: 53
Joined: 04 Mar 2014, 00:53
Number of books owned: 0
Country: ____

Re: Converting Color/Grayscale Text Scans to Black & White

Post by russca » 16 Oct 2015, 23:59

I've had so many unsatisfactory black & white scan results that I had to come up with a way of fixing them. I read about Screen/Multiply blending modes in one of the Photoshop Photography books I have for correcting over/underexposed pictures. I started experimenting with them for text scans and they worked. I've discovered the Threshold method by randomly trying every single option under Image Adjustments in Photoshop.

When converting Color or Grayscale image to Black & White using my tutorial,

1) The Threshold method produces a binary image consisting solely of pure black pixels and pure white pixels. Think of CCITT Group 4 compression Black & White TIFF image.
threshold-color-table.jpg
2) Using the Blending Modes method results in black & white image with shades of gray. That what gives the final image a smooth look.
In the below example there are extra 18 gray color variations in addition to pure black and white colors.
blending-modes-color-table.jpg

The two methods can be combined in "blending modes to threshold" sequence to produce a little better result.


'

BTW, both methods are good for removing bleeding-through text from scans.
sip-through-text.jpg

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest