Can someone explain the parameters of OpenCV Stitcher? - opencv

I'm trying to reduce the calculation time of my stitching algorithm. I got some images which I want to stitch in a defined order but it seems like cv::stitcher.stitch() function tries to stitch every image with every other image.
I feel like I might find the solution in the parameters of OpenCV Stitcher. If not maybe I have to modify the function or try something else to reduce calculation time. But since I'm pretty much a beginner, I don't know how. I know that using GPU might be a possibility but I just don't get CUDA running on Ubuntu at the moment.
It would be great if you could give me some advice!
Parameters for OpenCV Stitcher module:
Stitcher Stitcher::createDefault(bool try_use_gpu) {
Stitcher stitcher;
stitcher.setRegistrationResol(0.6);
stitcher.setSeamEstimationResol(0.1);
stitcher.setCompositingResol(ORIG_RESOL);
stitcher.setPanoConfidenceThresh(1);
stitcher.setWaveCorrection(true);
stitcher.setWaveCorrectKind(detail::WAVE_CORRECT_HORIZ);
stitcher.setFeaturesMatcher(new detail::BestOf2NearestMatcher(try_use_gpu));
stitcher.setBundleAdjuster(new detail::BundleAdjusterRay());
from stitcher.cpp:
https://code.ros.org/trac/opencv/browser/trunk/opencv/modules/stitching/src/stitcher.cpp?rev=7244

I want to stitch in a defined order but it seems like
cv::stitcher.stitch() function tries to stitch every image with every
other image.
cv::stitcher does not have a parameter to fulfil your requirement.
However, in the stitching_detailed.cpp sample you have the --rangewidth parameter. By setting it to 1, the algorithm will only consider adjacent image pairs (e.g. for pair 1-2 matches would be computed but not for pair 1-3)

Related

image preprocessing methods that can be used for identification of industrial parts name (stuck or engraved) on the surface?

I am working on a project where my task is to identify machine part by its part number written on label attached to it or engraved on its surface. One such example of label and engraved part is shown in below figures.
My task is to recognise 9 or 10 alphanumerical number (03C 997 032 D in 1st image and 357 955 531 in 2nd image). This seems to be easy task however I am facing problem in distinguishing between useful information in the image and rest of the part i.e. there are many other numbers and characters in both image and I want to focus on only mentioned numbers. I tried many things but no success as of now. Does anyone know the image pre processing methods or any ML/DL model which I should apply to get desired result?
Thanks in advance!
JD
You can use OCR to the get all characters from the image and then use regular expressions to extract the desired patterns.
You can use OCR method, like Tesseract.
Maybe, you want to clean the images before running the text-recognition system, by performing some filtering to remove noise / remove extra information, such as:
Convert to gray scale (colors are not relevant, aren't them?)
Crop to region of interest
Canny Filter
A good start can be one of this tutorial:
OpenCV OCR with Tesseract (Python API)
Recognizing text/number with OpenCV (C++ API)

Create/Apply grunge-vintage-worn- old-scratchy filters in iOS

Does anybody knows how to create/apply grunge or vintage-worn filters? I'm creating an iOS app to apply filters to photos, just for fun and to learn more about CIImage. Now, I'm using Core-Image to apply CIGaussianBlur, CIGloom, and the like through commands such as ciFilter.setValue(value, forKey:key) and corresponding commands.
So far, core image filters such as blur, color adjustment, sharpen , stylize work OK. But I'd like to learn how to apply one of those grunge, vintage-worn effects available in other photo editing apps, something like this:
Does anybody knows how to create/apply those kind of filters?
Thanks!!!
You have two options.
(1) Use "canned" filters in a chain. If the output of one filter is the input of the next, code things that way. It won't waste any resources until you actually call for output.
(2) Write your own kernel code. It can be a color kernel that mutates a single pixel independently, a warp kernel that checks the values of a pixel and it's surrounding ones to generate the output pixel, or a general kernel that isn't optimized like the last two. Either way, you can use GLSL pretty much for the code (it's pretty much C language for the GPU).
Okay, there's a third option - a combination of the two above options. Also, in iOS 11 and above, you can write kernels using Metal 2.

error detection on food packaging -using Open Cv

I am trying to determine when a food packaging have error or not error. Example
the logo " McDonald's " have error misprints or not, as the wrong label, wrong color..( i can not post picture )
What should I do, please help me!!
It's not a trivial task by any stretch of the imagination. Two images of the same identical object will always be different according to lightning conditions, perspective, shooting angle, etc.
Basically you need to:
1. Process the 2 images into "digested" data - dominant color, shapes, etcw
2. Design and run your own similarity algorithm between the 2 objects
You may want to look at Feature detectors in OpenCV: Surf, SIFT, etc.
Along a result I just found your question, so I think I come too late.
If not I think your problem car easily be resolved, it exists since years and is called Sikuli .
While it's for testing purposes, I have been using it in the same way as you need : compare a reference and a production image. Based on OpenCV it does it very well.

What should I do for multiple histograms?

I'm working with openCV and I'm a newbie in this field. I'm researching about Camshift. I want to extend this method by using multiple histograms. It means when tracking an object has many than one apperance (ex: rubik cube with six apperance), if we use only one histogram, Camshift will most likely fail.
I know calcHist function in openCV (http://docs.opencv.org/modules/imgproc/doc/histograms.html#calchist) has a parameter is "accumulate", but I don't know how to use and when to use (apply for camshiftdemo.cpp in opencv samples folder). This function can help me solve this problem? Or I have to use difference solution?
I have an idea, that is: create an array histogram for object, for every appearance condition that strongly varies in color, we pre-compute and store all to this array. But when we compute new histogram? It means that the pre-condition to start compute new histogram is what?
And what happend if I have to track multiple object has same color?
Everybody please help me. Thank you so much!

Interpolation and Morphing of an image in labview and/or openCV

I am working on an image manipulation problem. I have an overhead projector that projects onto a screen, and I have a camera that takes pictures of that. I can establish a 1:1 correspondence between a subset of projector coordinates and a subset of camera pixels by projecting dots on the screen and finding the centers of mass of the resulting regions on the camera. I thus have a map
proj_x, proj_y <--> cam_x, cam_y for scattered point pairs
My original plan was to regularize this map using the Mathscript function griddata. This would work fine in MATLAB, as follows
[pgridx, pgridy] = meshgrid(allprojxpts, allprojypts)
fitcx = griddata (proj_x, proj_y, cam_x, pgridx, pgridy);
fitcy = griddata (proj_x, proj_y, cam_y, pgridx, pgridy);
and the reverse for the camera to projector mapping
Unfortunately, this code causes Labview to run out of memory on the meshgrid step (the camera is 5 megapixels, which apparently is too much for labview to handle)
I then started looking through openCV, and found the cvRemap function. Unfortunately, this function takes as its starting point a regularized pixel-pixel map like the one I was trying to generate above. However, it made me hope that functions for creating such a map might be available in openCV. I couldn't find it in the openCV 1.0 API (I am stuck with 1.0 for legacy reasons), but I was hoping it's there or that someone has an easy trick.
So my question is one of the following
1) How can I interpolate from scattered points to a grid in openCV; (i.e., given z = f(x,y) for scattered values of x and y, how to fill an image with f(im_x, im_y) ?
2) How can I perform an image transform that maps image 1 to image 2, given that I know a scattered mapping of points in coordinate system 1 to coordinate system 2. This could be implemented either in Labview or OpenCV.
Note: I am tagging this post delaunay, because that's one method of doing a scattered interpolation, but the better tag would be "scattered interpolation"
So this ends up being a specific fix for bugs in Labview 8.5. Nevertheless, since they're poorly documented, and I've spent a day of pain on them, I figure I'll post them so someone else googling this problem will come across it.
1) Meshgrid bombs. Don't know when this was fixed, definitely a bug in 8.5. Solution: use the meshgrid-like function on the interpolation&extrapolation pallet instead. Or upgrade to LV2009 which apparently works (thanks Underflow)
2) Griddata is defective in 8.5. This is badly documented. The 8.6 upgrade notes say that a problem with griddata and the "cubic" setting, but it is fact also a problem with the DEFAULT LINEAR setting. Solutions in descending order of kludginess: 1) pass 'v4' flag, which does some kind of spline interpolation, but does not have bugs. 2) upgrade to at least version 8.6. 3) Beat the ni engineers with reeds until they document bugs properly.
3) I was able to use the openCV remap function to do the actual transformation from one image to another. I tried just using the matlab built in interp2 vi, but it choked on large arrays and gave me out of memory errors. On the other hand, it is fairly straightforward to map an IMAQ image to an IPL image, so this isn't that bad, except for the addition of the outside library.

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