I want to add line to image directly without a groups to make the line rasterized object (instead of a vector). The fact is that due to the large number of vector objects ( over 100) application work slow.
After drawing the lines, insert them to a group and convert them to a single display object using display.capture function
Have a look here http://docs.coronalabs.com/api/library/display/capture.html
Also take a look at
display.save
Related
I have a task where I need to detect power lines in the video. For example, here is an image taken from the video:
Line is bright target in the video, so I used close operation to make it more clear. Then I used LSDDetect to detect lines. Then I get a collection of detected lines which are represented by end points. Here is the result:
But because the background is complex, I got many small lines that I don't want. I can filter most of them out by defining line angle(approximately 90 degree) and view field（x coordinate value range）.
The problem is that the value is defined by me. How can I make the program calculate the proper angle and view field automatically? Or is there a better solution?
I'm new to opencv. Now I'm just using the library that opencv provides me, like the LSDDetect function, I don't know how they are implemented.
I'm currently trying to find a neat way of storing separate "branches" in a binary image. This little animation explains it:
As I go along the branches I need to collect the pixel indices that makes up a single-pixel wide branch. When I hit a junction point it should split up and store the new branches.
One way of going about it is maybe to create a 3x3 subregion, find out if there are white pixels inside it, move it accordingly, create a junction point if there is more than two. Always store the previous subregion so one can use it for making sure that we don't move to regions we already scanned.
It's a bit tricky to figure out how I would go about it though.
I basically need to reorder the pixels based on a "line/curve" hierarchy. Another part of the application will then redraw the figures, which internally works by creating lines between points hence the need to have them "ordered".
I don't know if you could apply it in your case but you should take a look at cv::findContour.
you will get a vector of points ordered.
http://docs.opencv.org/doc/tutorials/imgproc/shapedescriptors/find_contours/find_contours.html
I have a task where I need to track a series of objects across several frames, and compose the background from the image. The issue arises because one of the objects does not move until near the end, so I'm forced to take a shoddy average of the image. However, if I can blur out the objects, I think I'll be able to improve the background average.
I can identify a subsection of the image where the object is, an m by m array. I just need the ability to blur out this section with a filter. However, imfilter uses a fullsized array (image) as its input, so I cannot simply move along this array pixel by pixel in a for loop. But, if I try removing the image to take an image, I cannot put it back in without using another for loop, which would be computational expensive.
Is there a method of mapping a blur to a subsection of an image using MATLAB? Can this be done without using two for loops?
Try this...
sub_image = original_image(ii:jj,mm:nn)
blurred_sub_image = imfilter(sub_image, etc)
original_iamge(ii:jj,mm:nn) = blurred_sub_image
In short, you don't need to use a for loop to address a subsection of an image. You can do it directly, both for reading and writing.
I have two images that I want to display on top of each other. one image a single channel image and the second image is a RGB image but with most of the area being transparent.
How these two images are generated in different functions. I know to just display these on top of each other, i can use the same window name when calling cvShowImage() but this doesn't work when they are drawn from different functions. When trying this, I used cvCvtcolor() to convert he binary image from single channel to RGB and then displaying the second image from another function. But this didn't work. Both images are same dimension, depth and number of channels (after conversion).
I want to avoid passing in one image into the second function and then draw them. So I'm looking for a quick dirty trick to display these two images overlapped.
Thank you
EDIT:
I don't think that's possible. You'll have to create a new image or modify an existing one. Here's an article that shows how to do this: Transparent image overlays in OpenCV
There is no way to "overlay" images. cvShowImage() displays a single image from memory. You'll need to blend/combine them together. There are several ways to do this.
You can copy one into 1 or 2 channels of the other, you can use logical operations like AND, OR or XOR, you can use arithmetic operations like Add, Multiply and MultiplyScale (these operations will saturate values larger than 255). All these can also be done with an optional mask image like your blob image.
Naturally, you may want to do this into a third buffer so as not to overwrite your originals.
Apparently now it can be done using OpenCV 2.1 version
http://opencv.willowgarage.com/documentation/cpp/highgui_qt_new_functions.html#cv-displayoverlay
If I have a texture file how would I be able to load up only a part of it using a defined rect (top, left, bottom, right)?
Is it technically possibly to only read in the parts I want to load while leaving the rest of the texture untouched?
What exactly are you trying to achieve. Its pretty simple to load up only a small part of a file into a single texture that encompasses it all. You'll probably need to write your own image parser, though.
If you want to load a partial image into a texture thats the same size as the original image (ie only update the area you are after) then this is relaitvely simple as well. You can LockRcts with a rect that is the area you want you update. You'll still need to write your own image parser though.
Personally in situations like this I prefer to use my own texture format that is already in the format I'm after ...
Look at D3DXCreateTextureFromFileEx: http://msdn.microsoft.com/en-us/library/bb172802%28v=VS.85%29.aspx
Otherwise, load the portion of the data you require yourself into memory, create an empty texture and lock it and copy the data.