We Keep Coding

OpenCV numpy to cv::Mat conversion

I inherited an application with opencv, shiboken and pyside and my first task was to update to qt6, pyside6 and opencv 4.5.5. This has gone well so far, I can import the module and make class instances etc. However I have a crash when passing numpy arrays:
I am passing images in the form of numpy arrays through python to opencv and I am using pyopencv_to to convert from the array to cv::Mat. This worked in a previous version of opencv (4.5.3), but with 4.5.5 it seems to be broken.
When I try to pass an array through pyopencv_to, I get the exception opencv_ARRAY_API was nullptr. My predecessor solved this by directly calling PyInit_cv2(), which was apparently previously included via a header. But I cannot find any header in the git under the tag 4.5.3 that defines this function. Is this a file that is generated? I can see there is a pycompat.hpp, but that does not include the function either.
Is there a canonical way to initialize everything so that numpy arrays can be passed properly? Or a tutorial anyone can point me to? My searches have so far not produced any useful hints.
Thanks a lot in advance! :)

I finally found a solution. I dont know if this is the correct way of doing it, but it works.
I made a header file that contains
PyMODINIT_FUNC PyInit_cv2();
as a forward declaration and then copied over everything in the modules/python/src2 directory. I assumed this was already happening in the cv2.cpp file, because there is already exactly that line (in cv2.cpp).
But just adding that include works perfectly fine, apparently. Now I can call the init function when my own module is initialized and it seems to properly set all the needed state.

How can I call a python function from an advanced scripting voice command in Dragon NaturallySpeaking?

How can I call a python function from an advanced scripting voice command in Dragon NaturallySpeaking?
I don't want to use a third-party application such as dragonfly or NatLink (paper).

So, one way is to compile it. You can put a bunch of functions that do different things all into the same program and pass along appropriate arguments to select the function you want, and pass the parameters along. Returning the result can be tricky, though, but I usually use the Clipboard (so copy the py output to clip and read from clip in Dragon). Multi-word params need to have spaces escaped (%20) and process it inside your py.
Something like this:
ShellExecute "path\program.exe myFunc myPar1, my%20Par%202", 6 ' 6 runs minimized
Wait 1
myVar = Clipboard
Hth,

Warning: This is not an answer. I am not a programmer. I don't know any Python and have no way of testing it.
This is just a suggestion on how to solve this problem. I don't know where else to put this. I'd put it in a comment, but it allows no screenshots. Please edit and suggest as you wish.
There is answer on SO that deals with calling Python from Excel, which is a similar concept: https://stackoverflow.com/a/3569988/2101890. I am trying to use that here but don't know how.
When using commands in another programming language, you can sometimes add them by adding a reference in the MyCommands Editor. You can reference DLLs and other "stuff". Some references to libraries appear automatically. I've installed Python and hoped to find Python in the References, but no such luck:
There is no Python entry here that I can find. You may have better luck. If you do find something, check the box and see if you can add python commands without causing an error when saving the command.
Maybe you can browse to %localappdata%\Programs\Python\Python36\ and add some of the DLLs from there and call Python commands from there. Or try getting it to work in the way described under 1.

OpenCV 2.4.3 and Python

Few days ago I went into searching for a good way to make a simple computer vision system. OpenCV library is something I need but it proved hard to learn with Python especially after OpenCV 2.4.3 update which have very slim Python related documentation. So I now understand that there was a bunch of changes in OpenCV, for exaxmple
import cv
is now
import cv2
And there is bunch of modules that is missing. I mean, yes there are examples of the new python-opencv syntax but it's very narrow and proven to be hard to understand.
For example:
Example in official documentation for Python code
cv2.cvtColor(src, code[, dst[, dstCn]])
I know what this code means and how to use it, at least I think i know. But writing source and color code does nothing just give me :
Traceback (most recent call last):
File "C:\FILEFOLDER\tut.py", line 11, in <module>
cv.cvtColor('proba.jpg', 'CV_RGB2GRAY')
TypeError: an integer is required
Or if i try to write code like variable:
Traceback (most recent call last):
File "C:\FILEFOLDER\tut.py", line 11, in <module>
cv.cvtColor('proba.jpg', CV_RGB2GRAY)
NameError: name 'CV_RGB2GRAY' is not defined
So is there any Python related reference document/tutorial/book/guide for newest OpenCV with the ground up explanations that does not confuse newbie like me with unwanted code examples for C++ or Java?

I think you are taking it in the reverse path.
Actually, with the new cv2 module, OpenCV has become far more simple compared to old cv interface. Not just simple, but very fast and highly productive, due to the Numpy support. Only thing is that, we should know how to use it appropriately.
Here, you should use the function as follows :
img = cv2.imread('pic.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
I would like you to visit one SOF which shows some comparison between both the modules : What is different between all these OpenCV Python interfaces?
Another one SOF is here, which is a simple demonstration on how you can speed up the code with Numpy support : Performance comparison of OpenCV-Python interfaces, cv and cv2
You need not learn C++ or C to use OpenCV, although C++ is the official language. Still, Python-OpenCV has good support. Once you get a grip on how to use OpenCV, you will be able to convert C++ codes into Python yourself. Then you can learn OpenCV from C++ tutorials also. For example, I started learning OpenCV from "Learning OpenCV" by Gary Bradsky which is completely in C++. At that time, there was only cv interface.
As you mentioned in your comments, opencvpython.blogspot.com has some introductory tutorials. I started it focussing newbies in OpenCV.
Also, check this SOF for more tutorials : Books for OpenCV and Python?

To take it from another angle and allow you to run older code with new OpenCV installation versions...
First off the move from cv to cv2 has to do with the library using different data structures for a lot of functions. The easiest way to tell if a function has changed between cv2 and cv is that cv functions start with a capital. Reworked cv2 functions seem to always have the first letter in lowercase. So if you are using an old book or old examples, you can still use the legacy cv. cv is now simply embedded in cv2. Simply use the following at the top of your scripts
import cv2
import cv2.cv as cv #required for old code not to be changed
This allows you to simply run older code without changing it. I will demonstrate with your function call here. You had...
cv.cvtColor('proba.jpg', 'CV_RGB2GRAY')
The first thing I notice is that your function may be called wrong. (Given first letter of function is lower case it should start with cv2 not cv). Second is the 'code' you are passing the function. 'Codes' are members (coding noob here, forgive me if some of my vocab is inaccurate) of cv2 and cv but not always the same. You have 'CV_RGB2GRAY'. First off, no quotes. This is a cv 'code' not cv2. Also you are missing the 'cv.' in front. To demonstrate here is how I believe your function should be called for old cv version:
cv.CvtColor('proba.jpg', cv.CV_RGB2GRAY) #Assuming you used listed imports
cv2.cv.CvtColor('proba.jpg', cv2.cv.CV_RGB2GRAY) #Assuming you skipped second import
And now cv2...
cv2.cvtColor('proba.jpg', cv2.COLOR_RGB2GRAY)
There you go, I hope this helps. Remember that given python runs off of scripts you can type anything you are unsure of directly into command line. This does wonders for helping me build my understanding (I first used python 5 days ago). For example if you were wondering why it wanted an integer in your function, when you type
cv.CV_RGB2GRAY
directly into the python command line, it spits '7' (handy that it is an int) back at you. The cv2 version spits out '7L'. Just remember to use the WaitKey() function now and again in some form otherwise highgui may not have the required time to process some commands, in some situations. Well that wraps it up. Sorry if I covered some things that were already covered or referenced to. If I did feel free to delete it, admins.

What are the parameters for .GetWindow function in python?

I'm kinda new to programming, and I wanna write a simple program that needs to OCR a particular window. Currently, I'm using (w.GetForegroundWindow()), but that gets me the current window which would always be the Python shell, since that is the one that is active when I run it, even if it is for a split second only.
After searching around for a bit, I found the .Getwindows function, but not much of it on Python. What does it do, and what are the parameters? Will i be able to target a particular process (=window) with it? If not, what can I use then?
This is using the pywin32 module on Python 2.7 in Windows
I'm in Windows, Python 2.7 . The GetWindows function comes with the module pywin32, if im not wrong

The usual way is to call EnumWindows with a callback and then get information about each hwnd - for example name, title or window class. Check that against what you are looking for and save the matched hwnd. After EnumWindows returns, check that you found a valid hwnd and use that for your program.
It's not pleasant - there's not much support for this kind of thing in windows. I've heard that using accessibility features is better but I have no experience using that.

Pygame Segmentation error when using the SimpleCV library findBlob function

I have been using SimpleCV for find blobs to be used with a self-driving robot. The problem is when I call the findBlobs command in SimpleCV. When I completely block the lens of the Kinect Camera, PyGame crashes giving me this error:
Fatal Python error: (pygame parachute) Segmentation Fault
Sometimes it works and other times it just crashes, even when the lens is unblocked. It will almost always crash when i run it for longer than about thirty seconds.
I have re-installed and fixed many problems in SimpleCV and tried re-installing Pygame and it doesn't seem to help at all. Also, I am using the X-Box kinect as my camera source. I'm using Ubuntu 11.04.
Here is my exact code:
from SimpleCV import *
from SimpleCV.Display import *
from time import sleep
k = Kinect()
dis = Display()
while 1:
depth = k.getDepth()
depth = depth.invert()
depth = depth.erode()
blobs = depth.findBlobs(threshval=127, minsize=10, maxsize=0)
if blobs:
blobs.draw()
depth.save(dis)
sleep(0)

Kat here, I wrote the SimpleCV blob library.
There were a couple issues with the blob library that we found after we shipped the 1.1 release. The two big ones were that the blob library would hit the python max recursion depth and bail out. The second one stems from the actual underlying OpenCV wrapper and causes the pygame error when there are no blobs are detected by the blob maker.
The solution right now is to use the version that is in the master branch of our github repo. The patched version will also be available in the new SimpleCV 1.2 release which is slated for later this month. If you want to manually fix the code I have pasted the fixed snippet below:
In BlobMaker.py around line 55
def extractFromBinary(self,binaryImg,colorImg, minsize = 5, maxsize = -1):
#fix recursion limit bug
sys.setrecursionlimit(1000000)
if (maxsize <= 0):
maxsize = colorImg.width * colorImg.height
retVal = []
#fix all black image bug
test = binaryImg.meanColor()
if( test[0]==0.00 and test[1]==0.00 and test[2]==0.00):
return FeatureSet(retVal)
seq = cv.FindContours( binaryImg._getGrayscaleBitmap(), self.mMemStorage, cv.CV_RETR_TREE, cv.CV_CHAIN_APPROX_SIMPLE)
retVal = self._extractFromBinary(seq,False,colorImg,minsize,maxsize)
del seq
return FeatureSet(retVal)

Anthony one of the SimpleCV developers here:
Can you try changing the last line:
sleep(0.01)
Just to see if there is some type of issue going on where it can't process fast enough. I recently upgraded to Ubuntu 11.04 and I think there are a couple of python bugs I need to squash that popped up since 10.10.
Also if you could post this to our issue queue I would appreciate it:
http://github.com/ingenuitas/SimpleCV/issues

Fatal Python error: (pygame parachute) Segmentation Fault
This means that some code crashed, and now you need to debug it to find the problem. I assume you are learning something; might as well learn how to debug ;-)
Sometimes it works and other times it just crashes, even when the lens is unblocked. It will almost always crash when i run it for longer than about thirty seconds.
These are classic symptoms of heap corruption, or a data race.
I have re-installed and fixed many problems in SimpleCV and tried re-installing Pygame and it doesn't seem to help.
Why did you think it would? Your problem does not at all look like an installation problem.
So here is what you do: the tool for debugging heap corruption problems on Linux is valgrind. Run it like this:
valgrind python your-code.py
Unfortunately, default Python installation is not Valgrind-friendly, and above command will likely produce a lot of "uninitialized memory read" errors. You'll want to suppress most of them using this suppression file.
It may be possible to concentrate on errors that contain non-Python parts (and SimpleCV in particular). You are looking for invalid {read,write} ... N bytes after block ....
If you find such an error, you can try to debug it further with GDB, or report it to SimpleCV developers and hope for the best.
If you don't find the error, you can build a Valgrind-friendly version of Python (instructions), and try again.
If above run is Valgrind-clean, then you may have a race rather than heap corruption. Repeat with ThreadSanitizer.

Just replace your blob threshold with "-1"; I had the same problem and this fixed it.