Well I'm using a complied .NET version of this OCR which can be found # http://www.pixel-technology.com/freeware/tessnet2/
I have it working, however the aim of this is to translate license plates, sadly the engine really doesn't accurately translate some letters, for example here's an image I scanned to determine the character problems
Result:
12345B7B9U
ABCDEFGHIJKLMNUPIJRSTUVHXYZ
Therefore the following characters are being translated incorrectly:
1, O, Q, W
This doesn't seem too bad, however on my license plates, the result isn't so great:
= H4 ODM
= LDH IFW
Fake Test
= NR4 y2k
As you might be able to tell, I've tried noise reduction, increasing contrast, and remove pixels that aren't absolute black, with no real improvements.
Apparently you can 'learn' the engine new fonts, but I think I would need to re-compile the library for .NET, also it seems this is performed on a Linux OS which I don't have.
http://www.scribd.com/doc/16747664/Tesseract-Trainingfor-Khmer-LanguageFor-Posting
So I'm stuck as what to try next, I've wrote a quick console application purely for testing purposes if anyone wants to try it. If anyone has any ideas/graphic manipulation/library thoughts, I'd appreciate hearing them.
I used Tesseract via Tessnet2 recently (Tessnet2 is a VS2008 C++ wrapper around Tesseract 2.0 made by Rémy Thomas, if I remember well). Let me try to help you with the little knowledge I have concerning this tool:
1st, as I said above, this wrapper is only for Tesseract 2.0, and the newest Tesseract version on Google Code is 3.00 (the code is no longer hosted on Source Forge). There are regular contributors: I saw that version 3.01 or so is planned. So you don't benefit from the last enhancements, including page layout analysis which may help when your license plates are not 100% horizontal.
I asked Rémy for a Tessnet2 .NET wrapper around version 3, he doesn't plan any for now. So as I did, you'll have to do it by yourself !
So if you want to get the latest version of the sources, you can download them from the Subversion repository (everything's described on the dedicated site page) and you'll be able to compile them if you have Visual Studio 2008, since they sources contain a VS2008 solution in the vs2008 sub-folder. This solution is made of VS2008 C++ projects, so to be able to get results in C# you'll have to use .NET P/Invoke with the tessDll built by the project. Again if you need this, I have code examples that may interest you, but you may want to stay with C++ and do your own new WinForm projects, for instance !
When you have achieved to compile (there should not be major problems for that, but tell me if you meet some, I may have met them too :-) ), you'll have in output several binaries that will allow you to do a specific training ! Again, there is a page specially dedicated to Tesseract 3 training. Thanks to this training, you can:
restrain your set of characters, which will automatically remove the punctuation ('/-\' instead of 'A', for instance)
indicate the ambiguities you have detected ('D' instead of 'O' as you could see, 'B' instead of '8' etc) that will be taken into account when you will use your training.
I also saw that Tesseract results are better if you restrain the image to the zone where the letters are located (i.e. no face, no landscape around): in my case, I needed to recognize only a specific zone of cards photos taken from a webcam, so I used image processing to restrain the zone. That was long, of course, but my images came from many different sources so I had no choice. If you can get images that are restrained to the minimum, that will be great !
I hope it was of any help, do not hesitate to give me your remarks and questions !
Hi I've done lots of ocr with tesseract, and I have had some of your problems, too. You ask about IMAGE PROCESSING tools, and I'd recommend "unpaper" (there are windows ports too, see google) That's a nice de-skew, unrotate, remove-borders-and-noise and-so-on program. Great for running before ocr'ing.
If you have a (somewhat) variable background color on your images, I'd recommend the "textcleaner" imagemagick script
I think it's edge detecting and whitening out all non-edgy stuff.
And if you have complex text then "ocropus" could be of use.
Syntax is (on linux): "ocroscript rec-tess "
My setup is
1. textcleaner
2. unpaper
3. ocroups
With these three steps I can read almost anything. Even quite blurry+noisy images taken in uneven lighting, with two columns of tightly packed text comes out very readable. OK maybe your needs aren't that much text, but step 1) & 2) could be of use to you.
I'm currently building a license plate recognition engine for ispy - I got much better results from tesseract when I split the license plate into individual characters and built a new image displayed vertically with white space around them like:
W
4
O
O
M
I think a big problem that tesseract has is it tries to make words out of the horizontal letters and numbers and in the case of license plates with letters and numbers mixed up it will decide that a number is a letter or vice versa. Entering an image with the characters spaced vertically makes it treat them as individual characters instead of text.
A great read! http://robotics.usc.edu/publications/downloads/pub/635/
About your skew problem for license plates:
Issue: When OCR input is taken from a hand-held camera
or other imaging device whose perspective is not fixed like
a scanner, text lines may get skewed from their original
orientation [13]. Based on our experiments, feeding such a
rotated image to our OCR engine produces extremely poor
results.
Proposed Approach: A skew detection process is needed
before calling the recognition engine. If any skew is detected,
an auto-rotation procedure is performed to correct the skew
before processing text further. While identifying the algorithm
to be used for skew detection, we found that many
approaches, such as the one mentioned in [13], are based on
the assumptions that documents have s et margins. However,
this assumption does not always hold in our application.
In addition, traditional methods based on morphological
operations and projection methods are extremely slow and
tend to fail in presence of camera-captured images. In this
work, we choose a more robust approach based on Branchand-
Bound text line finding algorithm (RAST algorithm) [25]
for skew detection and auto-rotation. The basic idea of this
algorithm is to identify each line independently and use the
slope of the best scoring line as the skew angle for the entire
text segment. After detecting the skew angle, rotation is
performed accordingly. Based on our experiments, we found
this algorithm to be highly robust and extremely efficient
and fast. However, it suffered from one minor limitation in
the sense that it failed to detect rotation greater than 30.
We also tried an alternate approach, which could detect any
angle of skew up to 90. However, this approach was based
on presence of some sort of cross on the image. Due to
the lack of extensibility, we decided to stick with RAST
algorithm.
Tesseract 3.0x, by default, penalizes combinations that aren't words and aren't common words. The FAQ describes a method to increase its aversion to such nonsense. You might find it helpful to turn off the penalty for rare or nonexistent words, as described (inversely) here:
http://code.google.com/p/tesseract-ocr/wiki/FAQ#How_to_increase_the_trust_in/strength_of_the_dictionary?
If anyone from the future comes across this question, there is a tool called jTessBoxEditor that makes teaching Tesseract a breeze. All you do is point it at a folder containing sample images, then click a button and it creates your *.learneddata file for you.
ABCocr .NET uses Tesseract3 so that might be appropriate if you need the latest code under .NET.
Related
Back in the late eighties I seem to remember using a unix utility method named 'banner' - (see http://en.wikipedia.org/wiki/Banner_(Unix) It basically took a string of text and 'rendered' it as a larger text 'banner' using each character as blocks to form the original character. It was usually used at the start of print runs to create a heading for multi-sheet reports.
Does anyone know of a C# library that reproduces this functionality?
I remember a similar thing on the VAX mainframes at college. useful with a roomful of people banging in Pascal programs on VT100 terminals, and only one matrix printer behind closed doors in the hallowed office where the IT staff worked.
Anyway, this is a C# ASCII art creator - if you could find a way of rendering your text to a graphic file you could then convert it.
You probably could invoke a free software C program doing the same, perhaps figlet
I'm developing an application for Windows Phone that are using different kinds of math problems, such as hard equations. The thing is that I want this app to be nice and cool and therefor It's obviously that you can't use the * (snowflake) as the multiplication symbol and you can't use the ^ (roof-top) as the exponent symbol. No, what I want is that I want to parse equations into cool images. I mean like this:
I know that there are several ways to parse math, including Latex, MathML and many more, I do also know that there are many javascript based strategies to create images like this, but I still haven't found one that are compatible with Windows Phone 7 based on C#. And I don't want to have anything server based, I want the conversion between equation to an image to be done in the client.
If you have any suggestions please leave a answer.
So the "*" becomes a "."? Not sure whether that's cooler or not but you still don't need an image generator, a nice font will do.
this is a pretty rough area (fuzzy logic image comparison) that is way
above my pay grade, so to speak.
I'm trying to write a program that will detect carrots (and other veggies) onscreen from a game and return matching x,y coordinates for each found match.
The intent is to track each time the vegetable grows (5 times) and eventually automate the watering/harvesting of the vegetables (once you see the screenshots this will make more sense).
I tried using the image compare code located at
http://sites.google.com/site/serinolorenzo/blackmask
it actually works flawlessly when searching this screenshot (and desktop grabs)
http://imageshack.us/photo/my-images/24/mac8.png/
for instances this image...
http://imageshack.us/photo/my-images/249/carrotplant.png/
It does find and return multiple "Carrot Seeds" menu coordinates.
However when I get down to detecting the veggies (the meat and potatoes of what the compare needs to detect) it fails to find a match.
I've tried various "carrot" screenshot, most recently...
http://imageshack.us/photo/my-images/829/carrotlight1t.png/
to the image
http://imageshack.us/photo/my-images/408/macnolight1.png/
(I had to turn in game lighting off when I got here, to ensure colors stayed the same regardless of game time).
I thought (by going over the source code for the image compare) that black would be ignored, so I'm not sure exactly what's going on, but it just will not find a match now, even if I set the thresholds lower.
Are there any (well documented) libraries that exist to do this, as coding it from scratch is just something I can't do at the moment.
Barring that (and if whomever is reading this has the time) can you see where I'm going wrong?
The code I'm using to do the testing is...
public void tester()
{
Bitmap screenshot;
screenshot = new Bitmap(#"c:\MyMercurial\ATITDVeggieMacro\ATITDVeggieMacro\Images\macnolight1.bmp");
Bitmap searchFor;
searchFor = new Bitmap(#"c:\MyMercurial\ATITDVeggieMacro\ATITDVeggieMacro\Images\wholecarrot.bmp");
int ac1;
int ac2;
ArrayList test = BlackMask.Search(screenshot,searchFor,
0,10,75,5,80,20,100,true,out ac1,out ac2);
statusUpdate = ac1.ToString()+"good,"+ ac2.ToString()+" bad/ X=";
}
(I just update the file paths when I want to change images).
(Bonus question, how to I use relative paths to tell it to just go up two directories and then down into the Images folder, I can't at all remember the relative path shortcuts)
Thanks for any help guys, this ones got me slamming my forehead.
For intelligent image processing in .NET, you could look into using AForge.NET. There's also OpenCV, but then are no .NET bindings that I know of off hand (they appear to have some for Java though...). Once you figure out which library, I'm sure you can find additional articles via Google on their usage (besides their standard examples)
I've never played ATITD, however, if you figured out the various specs of how it was developed, that could shed some light into how you might approach this problem in an entirely different direction. For example, if their Client app links to the MS C runtime DLL, it might have been developed in C/C++ (or maybe with some other lang whose framework runs on a C/C++ core). You could end up just manipulating the memory of the program if you found out how it stores the copy of the game state in the Client memory (assuming it's just not some video feed, a la OnLive). If you figure out which rendering framework they use, OpenGL, DX, etc, you may be able to do the image capture more efficiently (and possibly without as much artifacts, like the grass and such, that you have to mask out yourself) via DLL hooks/proxies.
I am trying to use Graphics.DrawString and TextRenderer.DrawText to laydown on a fixed rectangle some strings with variable number of characters.
However, even using the GDI+ wrapping methods I am not satisfied with result: I would need to control the font kerning (or string character spacing) to give a chance to pack high number of characters strings.
I read about FontStretches but I do not know how to use in winform. Another method is Typography.SetKerning but again I am blank about using it.
Can someone help?!
Round 2:
I know it could be hard, Win32 API has a freetype support which could be the solution to issue.
Practically my aim is to do something similar to "http://stackoverflow.com/questions/4582545/kerning-problems-when-drawing-text-character-by-character", in .NET. Notice that I am working on pre-formed string of arabic language, not user character imput.
My problem is:
(1) identify which library has the wanted kerning function (most probably gdi32.dll), (2) build a c# safe environment to deal with dll calls, (3) implement a call to dll that works in c#.
Can someone help?
Thank you for answering.
If you look at the documentation, its quite easy to find out which does what, and how to use it.
The method Typography.SetKerning is an WPF-only thing, so you won't be able to use it in WinForms.
A quick Google found this article, which shows us how to modify kerning values to GDI text.
For a Windows CE project that we print slips, we have a new request which asks if it is possible to print a line insted of printing "-----------" all the way.
Is this possible without printing an image?
c# / .net 3.5
Thank you
On your desktop run charmap.exe. Tick "Advanced view" and type "box" in the Search box. You'll get the Unicode codepoints that you can use to draw lines and boxes. Copy and paste them into your code. Whether they actually show up properly on your device depends on the font support. Odds are decent since they've been around since the first IBM PC. You'll have to try.
There are extendedascii values to do this (196) but it really depends on the printer.
Or as quppa comments use _ but it will not be adequate if you want to box in a title or so.
Wikipedia has an article on box-drawing characters.
Since ─ (U+2500) didn't work for you, it's unlikely ━ (U+2501) will work either, but it's perhaps worth a shot. There is also no guarantee that there won't be spaces between these characters, given that spaces appear between underscores.
The issue is not Windows CE supporting Unicode but finding a font that you can use that has the box-drawing characters. Given the likely size limitations (fonts with lots of characters are tens of megabytes big), this might be a challenge.