Develop Reference

Does anyone know any API for OCRing 7-Segment Display for Windows Phone?

I'm trying to develop a Windows Phone 8.1 App but I need to recognize some numbers from different Displays.
I was following this example:
http://bsubramanyamraju.blogspot.com/2014/08/windowsphone-81-optical-character.html
That is using the Microsoft OCR Runtime Library:
https://www.nuget.org/packages/Microsoft.Windows.Ocr/
However, it doesn't work when I'm trying to recognize those kinds of pics. Even I found this site:
https://www.unix-ag.uni-kl.de/~auerswal/ssocr/
Does anyone have a recommendation? Or Does anyone know any code related to it?
Thank for your worthy knowledge.

I wish the answer to your question would be "Sure, here it is" with link to a black-box process-anything OCR tool, but there are several aspects involved, which are best considered separately.
First, there is some work on image pre-processing BEFORE you even consider any OCR. Your image samples are very drastically different, and include full range of issues.
SAMPLE 1 has low contrast, so when it is binarized to black and white layer, which most OCR will perform internally at some stage, there are no characters to process. It looks like this after binarization:
See this OCR Blog post for additional details on image pre-processing: http://www.ocr-it.com/guide-to-better-mobile-images-from-cell-phone-camera-for-higher-quality-ocr.
Secondly, the image has no dpi information in the header, which some OCR technologies use to determine appropriate scaling of the image. Without header information, some OCR programs may set some default dpi, which may or may not match your image, thus affecting the OCR result. This is NOT critical, but preferred if this can be implemented at the time of picture creation.
SAMPLE 2 has sufficient contrast and adaptive notarization returns a clear image. It is also missing dpi resolution value in the header.
SAMPLE 3 has very clear contrast, but it also has no resolution dpi in the header.
Once you have images that are optimized for OCR processing, the next step is to look at OCR technologies.
I did NOT test the once you mentioned, assuming you had correct implementation and yet no success with them. I tested other OCR tools I have used in the past.
In general, there is no 7-segment OCR known to me. However, I was able to adapt to other generic OCR for this specialized task. Every OCR I tried'out-of-box' or with default settings is unable to handle this recognition. And it is logical and expected. Why? Because most generic OCR are written to recognize inseparable pixel patterns for each character. This is related to the "character separability" principle used to separate words into separate characters. In other words, inner OCR algorithms look for connected strokes which make up each character. More powerful commercial OCR allows some breaks in pixel patterns, but they are expected to be minimal to none, like defects in print or scan, which may result in missing character pieces.
7-segment display by nature will have multiple breaks in each character, conflicting with the character separability principle.
More powerful OCR technologies have a) more tolerance to breaks in pixel patterns and/or b) have special settings to handle these cases.
I will perform further testing with OCR-IT web-based OCR API platform, which is well known to me. I worked as a developer on its OCR capabilities. I also use it extensively in my own iOS and Android apps. OCR-IT API is based on a strong commercial OCR engine, so it is having good tolerance to character imperfections as well as some controls to help in this case.
SAMPLE 3. This is the easiest sample to process, so I tested it first. Using OCR-IT API, and making a request with default settings, requesting the output to TXT format, I get the following:
It appears that OCR is a) segmenting characters into two separate lines, and b) tries to read resulting patters as close as possible to valid characters.
Based on this quick analysis, making one adjustments to OCR settings results in the following recognition:
The setting that made substantial difference in OCR result is switching from default print type to using "DotMatrix", which is in the middle of this entire OCR-IT API settings XML:
<Job>
<InputURL>http://i.stack.imgur.com/wOtFx.jpg</InputURL>
<CleanupSettings>
<Deskew>false</Deskew>
<RemoveGarbage>false</RemoveGarbage>
<RemoveTexture>false</RemoveTexture>
<RotationType>NoRotation</RotationType>
</CleanupSettings>
<OCRSettings>
<PrintType>DotMatrix</PrintType>
<OCRLanguage>English</OCRLanguage>
<SpeedOCR>false</SpeedOCR>
<AnalysisMode>MixedDocument</AnalysisMode>
<LookForBarcodes>false</LookForBarcodes>
</OCRSettings>
<OutputSettings>
<ExportFormat>Text</ExportFormat>
</OutputSettings>
</Job>
The use of DotMatrix print type turned on necessary algorithms to increase tolerance for breaks in character structure, which commonly occurs by nature of dot-matrix printers in dot-matrix prints. Alternatively, a "Typewriter" print type could be used, since character breaks are also expected in typewritten fonts, thus being automatically handled by OCR.
There could be one more change to the API setting to run OCR using "Digits" character set (language), effectively eliminating any possibility of misreading 1 as I, etc.
SAMPLE 2. In this sample, the gaps in each character's structure are much wider. Even standard algorithms for handling DotMatrix or Typerwriter print types cannot accommodate these wide gaps. The use of all possible setting variations returned something like this:
Character segmentation seems to be the issue. One technical solution goes back to image pre-processing. A simple algorithm can be implemented to fill in gaps between each segment of the 7-segment character. It does not have to be very precise, something like this:
But that is enough to produce a perfect OCR result.
Since it may be unknown in advance which 7-segment LCD display will require filled in gaps, and which does not, I recommend applying this algorithm to all LCD 7-segment images, with small or large gaps. I would limit the size of the gap to no wider than the width of a segment. Given these screens come in various background and segment colors, this pre-procession algorithm can be substantially simplified if it is performed on binarized (black & white) image.
Overall, this task is possible with OCR and near out-of-box functionality, assuming that some image pre-processing is performed. In general, I believe that image pre-processing is required for any OCR-related project anyway, specific to that project.
If you have any further questions about OCR or image pre-processing, pm me.

Despite it has been a while since Ilya's answer and thanks to his advice and other ones, especially this one:
Seven Segment Optical Character Recognition
I was able to create my own class in C#:
https://github.com/FANMixco/7-segment-ocr-reader/blob/master/OCR/SevenSegmentOCR.cs
Feel free to use it and improve it.

Dicom Images non square

I'm working with a set of DICOM images that are 512(columns) X 384(rows)
Is there a tool that would make the images 512X512? That is, filling the rows in this case to make it 512.
I've researched VTK with no luck.
Thanks!

Argh, you was almost there! In fact, VTK is not the proper tool for that. ITK is.
To be precise, VTK is for 3D visualization (that is, rendering of 3D objects), while ITK is specifically concerned for image processing.
So, using ITK, you could use a padding filter, here's a complete example from the official wiki, ready to be compiled and executed: http://public.kitware.com/pub/itk/Examples/src/Filtering/ImageGrid/PadAnImageWithAConstant/Documentation.html.
But, if you want to do the things in an easier way, I suggest MATLAB (ITK could be difficult to configure). In this case, this post could help: Padding an image in MATLAB.
Good luck!

How can I display mathematical expressions in WPF labels or panels?

I am writing software which displays a lot of mathematical content. As in windows forms it is already hard to set a subscript or a Greek letter in a label, I am thinking of switching to WPF.
At the moment I am searching for the best way to render a mathematical expression, a formula or just a symbol inside my graphical user interface. They have to be shown in labels or drawn graphs/pictures. No live/just-in-time renderings but beautiful fix symbols.
What is the best way to do that? I thought, that MathML should be supported well, but I can't find a lot regarding that. I would be glad to hear some advice.
Here is, where I can get my symbols from (or what I would prefer):
LaTeX-code (First choice! Code is already there and same appearance in Software and documentation would be marvellous)
MathML-code (LaTeX-code in Word 2007 or higher -> Word equations -> copy as plain MathML to clipboard)
SVG (some rendering of LaTeX in Inkscape and export to XAML)
xmcd Files (Mathcad XML Document. Don't know how, but at least it's XML)
html Files (written by LaTeX->html or Mathcad->html
What I wouldn't consider personally, but maybe there are good solutions to:
Images (png-icons, pdf, dvi, eps, svg directly imported)
Symbols (like copy pasted from Character Map. Don't like the fonts, wouldn't find all I need and exchange of formula syntax would not be given)
I think using LaTeX, MathML or html would be great as they could be used for documentation as well. I also could think about exporting calculation results to *.tex files or internally generate graphics completely with LaTeX (tikz, pgfplots...)

Consider using open-source WPF-Math library (disclaimer: I'm its' current maintainer).
It can help you to display the LaTeX expression in a WPF window. It also uses vector graphic instead of bitmaps, so the formulae will scale nice on the modern displays.

I would go with pure xaml approach using datatemplates. There is no need for another vector format or rednering engine.
You can use datatemplate for each expression in expression tree. Using viewboxes you can achieve stretching, so topmost expressions will be larger then inner expressions. Your datatemplates will generate visual tree from you expression tree. I mean there will be contentpresenters inside contentpresenter.
The great advatage is that the expression visualisation can be responsive and interactive, just like math expression in MS Word, or Excel.
I could help you with implementation, since this is not trivial, if you are not familiar with wpf datatemplates

As far as I can see, the best rendering (on paper) is achieved with a late conversion from a vector file. I would prefer using either GDI+ (System.Drawing) or WPF (System.Media) to render a formula. Let me know if we can collaborate on a WPF solution.

I used https://github.com/std8590/xmcd2cs to convert most of my Mathcad xmcd files to C#.
Then I used the formulas in code and make the input variables available in UI.

C# extracting character from screenshot image

I'm looking for some hints how to manage to get single character (in this case number) from screenshot (from flash game). I've tried almost all most popular commercial/non-commercial software but none of them can handle with a single character. I've been trying Office Document Imaging, LeadTools, Tesseract-OCR, Aspose.OCR. I enclosed the image, a screenshot from the game with given number:
http://desmond.imageshack.us/Himg831/scaled.php?server=831&filename=44739012.png&res=landing
For me it was obvious that OCR will work but I've been surprised, OCR can't handle with this.
Well you think it's impossible to use OCR to extract this number? Maybe you know some solution for my problem?
Another option is to use image comparing method but this is too slow, I'd prefer not use it.

Microsoft OneNote automatically parses all characters in images stored in it. Just paste in an image (or use Windows-S to fire up OneNotes screen grab).
Just right click and use Get Text from Picture.
Although it thinks your image contains
‚3

Locating Text within image

I am currently working on a project and my goal is to locate text in an image. OCR'ing the text is not my intention as of yet. I want to basically obtain the bounds of text within an image. I am using the AForge.Net imaging component for manipulation. Any assistance in some sense or another?
Update 2/5/09:
I've since went along another route in my project. However I did attempt to obtain text using MODI (Microsoft Office Document Imaging). It allows you to OCR an image and pull text from it with some ease.

This is an active area of research. There are literally oodles of academic papers on the subject. It's going to be difficult to give you assistance especially w/o more deatails. Are you looking for specific types of text? Fonts? English-only? Are you familiar with the academic literature?
"Text detection" is a standard problem in any OCR (optical character recognition) system and consequently there are lots of bits of code on the interwebs that deal with it.
I could start listing piles of links from google but I suggest you just do a search for "text detection" and start reading :). There is ample example code available as well.

recognizing text inside an image is indeed a hot topic for researchers in that field, but only begun to grow out of control when captcha's became the "norm" in terms of defense against spam bots. Why use captcha's as protection? well because it is/was very hard to locate (and read) text inside an image!
The reason why I mention captcha's is because the most advancement* is made within that tiny area, and I think that your solution could be best found there.
especially because captcha's are indeed about locating text (or something that resembles text) inside a cluttered image and afterwards trying to read the letters correctly.
so if you can find yourself a good open source captcha breaking tool you probably have all you need to continue your quest...
You could probably even throw away the most dificult code that handles the character recognition itself, because those OCR's are used to read distorted text, something you don't have to do.
*: advancement in terms of visible, usable, and practical information for a "non-researcher"

If you're ok with using an online API for this, the API at http://www.wisetrend.com/wisetrend_ocr_cloud.shtml can do text detection in addition to just OCR.

Stroke width transform can do that for you. That's at least what MS developed for their mobile phone OS. A discussion on the implementation is here at https://stackoverflow.com/