I tried to use guided filter( in OpenCV it's named guidedFilter ) to make a edge-preserving filter.And the guid image I used is as the same as the input image. I am not familiar with the choice of guided image.So anyone could give me some advice on it? thanks!
You can use practically everything as a guide. In raytracing it usually makes sense to use normal information and depth information as a guide, so the guide would be an RGBD-Image. OpenCV 3.0 seems to have a limit of 3 channels, which means you can only use an RGB-Image as a guide, where RGB corresponds to any kind of information not just red green blue color.
Here is one of the original papers on Guided Image Filtering if you do have some technical knowledge: He: Guided Image Filtering
Related
I want to use a custom shaped window using gtk3. I found gtk_widget_shape_combine_mask_() in gtk2. The closest thing I can find in gtk3 is gdk_window_shape_combine_region_(), which only allows for rectangular shaped regions. Why was the support dropped? Or was it changed and implemented in a different way?
What do you mean with "why was the support dropped?".
gtk_widget_shape_combine_mask() only supports rectangular shapes, too. That's what a GdkBitmap is: An image with a bit depth of 1. This means that a pixel is either included or not.
This is basically the same as a cairo_region_t. The difference is only in how the data is stored: Instead of a bitmap, cairo_region_t uses a list of rectangles to describe the same result.
"Or was it changed and implemented in a different way?"
Yes and you already found the replacement yourself.
I've already made a function to cut out the image, and the part I cut out has a black background. I'm trying to make the black part transparent, then I can generate an image sequence that I can create a video with. I've tried converting the image to a double and then replacing the 0 values with NaN:
J = imread('imgExample.jpg');
J2 = im2double(J);
J2(J2 == 0) = NaN;
imwrite(J2, 'newImg.jpg');
but when I convert it into a video, it doesn't seem to stay. Is there any way to get the black part of the image to be transparent?
From clarifications in comments, you are trying to create a video format that supports alpha transparency using matlab.
In general this seems impossible using matlab alone (at least in matlab 2013 which is the version I use). If you'd like to check if the newest matlab supports videos with alpha transparency, type doc videowriter and have a look at the available formats. If you see anything with transparency options there, take it from there. But the most I see on mine is 24bit RGB videos (i.e. three channels, no transparency).
So matlab does not have the ability to produce native .avi video with alpha transparency.
However, note that this is a very rare video format anyway, and even if you did manage to produce such a video, you would still have to find a suitable viewer which supports playing videos with transparency!
It's therefore important for you to tell us your particular use-case because it may be you're actually trying to do something much simpler (which may or may not be solvable via matlab) (i.e. a case of the XY Problem
E.g. you may be trying to create a video with transparency for the web instead, like here https://developers.google.com/web/updates/2013/07/Alpha-transparency-in-Chrome-video
If this is the case, then I would recommend you attempting the method outlined there; you can create individual .png "frames" with transparency in matlab using the imwrite function. have a look at its documentation, particularly the section about png images and the 'Alpha' property. But beyond that, you'd need an external tool to combine them into a .webm file, since matlab doesn't seem to have a tool like that (at least none that I can see at a glance; there might be a 3rd-party toolkit if you look on the web).
Hope this helps.
I am trying to align an atlas on a brain section via shape similarity. I converted both images to grayscale and filled them in white like so:
Section:
Atlas:
I tried aligning them by similarity using imregtform. However I get the error "Registration failed because optimization diverged." Is there a value in the optimizer that needs to be changed?
Or is there an easier way to do this in MATLAB?
I do not actually have the Image Processing Toolbox, but you should take a look at some of the help files. For instance, Mathworks has many sections online discussing how you can do image processing, including alignment. This link is somewhat a top level discussion (http://www.mathworks.com/help/images/index.html#spatial-transformation-and-image-registration) and this seems like it might be a great tool for you to do image alignment using the control point alignment technique (http://www.mathworks.com/help/images/point-mapping.html).
I hope this helps point you in the right direction. With out having the toolbox, I can't try the suggested tools.
Unfortunatly, Matlabs image registration only offers linear (geometric) transformations atm. That is, only translation, rotation, scale, and shear is allowed. This is not enough for your images since you have local distortions.
What you need is a non-rigid (elastic) registration. You can find some codes for this in the file-exchange.
I have table of l,a,b values and want to visualise these colors in matlab (or any other suitable software). Is there any quick way like series of rectangles filled with color values from the table?
There are several versions of the Lab color space, but presumably you're referring to most common, CIELAB. You can use imwrite in Matlab to create a TIFF image with 'cielab' specified for the 'Colorspace' option. I wouldn't trust Matlab as a viewer for the resultant images though. Photoshop in lab mode (from the menu bar: Image > Mode > Lab Color) would be a good choice if you want work with and see the closest thing to the actual CIELAB space. Other viewers/editors may convert to RGB or CMYK before rendering to the screen (likely without warning you), but maybe you don't mind. If you just want to convert from CIELAB to RGB, you might find these functions useful.
After lots of research, I found out there is a plugin called 'color inspector' that can be used along with ImageJ (all opensource tools). Have excellent capacity to view and analyse different color space. Even it has some color tools that matlab yet to have. here is imageJ: http://rsbweb.nih.gov/ij/download.html
and the plugin
http://rsb.info.nih.gov/ij/plugins/color-inspector.html
Hope this is useful to someone
I'm a newbie to Matlab. I'm basically attempting to manually segment a set of images and then manually label those segments also. I looked into the imfreehand(), but I'm unable to do this using imfreehand().
Basically, I want to follow the following steps :
Manually segment various ROIs on the image (imfreehand only lets me draw one segment I think?)
Assign labels to all those segments
Save the segments and corresponding labels to be used further (not sure what format they would be stored in, I think imfreehand would give me the position and I could store that along with the labels?)
Hopefully use these labelled segments in the images to form a training dataset for a neural network.
If there is some other tool or software which would help me do this, then any pointers would be very much appreciated. (Also I am new to stackoverflow, so if there is any way I could improve on the question to make it clearer, please let me know!) Thanks!
Derek Hoiem, a computer vision research at the University of Illinois, wrote an object labelling tool which does pretty much exactly what you asked for. You can download it from his page:
http://www.cs.illinois.edu/homes/dhoiem/software/index.html