I've drawn a lot of scattered pixels on a screen. I want to move them all a few pixels to the left. Doesn't matter what's left on the last columns of pixels – I can deal with them after the fact.
I tried using SetPixel to redraw the translated image, and though it worked, it wasn't as fast as I would have wanted. So I started searching the web for a specific function for my purpose. I came across SetWorldTransform, but from what I can gather, this serves only to translate coordinates, not full regions. I also found OffsetRgn, but again, this seems to have another purpose. I haven't found anything else that seems promising.
Is there anything I can do that's faster than the naive SetPixel?
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I am placing icons with a fixed diameter/radius on a line using d3.scaleTime. This works well except for the case in which dates are close to one another, leading to an unwanted overlap.
In that specific case, I would want the icons to "relax" and not touch.
My code rather complex, including animations etc. — so I drew the problem here:
These are my attempts:
I looked at d3-force for collision prevention, but I was not quite sure how to merge such an approach with an existing time scale. Could this be helpful? http://jsbin.com/gist/fee5ce57c3fc3e94c3332577d1415df4 However, it may occur that the icons then do not align on a horizontal straight line anymore, which is a disadvantage, because I do not want them to spread vertically.
I also thought about calculating overlaps and then manually adjusting the data so that the overlap does not occur. That, however seems a bit more complex because I would have to somehow recursively find the best position for every icon.
Could interpolation help me? I thought there must be something like "snap to grid", but then two icons could snap to the same position, couldn't they?
Which d3 concept makes most sense to solve this problem?
i am looking for a way to draw alot of paths fast in JavaFx8, the thing is I want to animate the paths.
I tried the standard path, polyline, I also tried drawing in an graphic context/canvas. But everything is just too slow.
In a test I am rotating around 200 Rectangles 1px wide and this works perfect, if I look in the pulselogger output I see that everything gets renderd within 16ms. In comparison if I draw 200 straight lines with the path node (same visual Output as 1px Rectangles) and animate this, i am getting very bad results and the paint task in the pulselogger shows 200ms.
I guess the problem is that the path is not drawn via OpenGl instead it falls back to SW renderning.
I use alot of lineTo() in the paths I want to render, so a very unelegant way would be to draw only the round stuff with the Path node and place a rectangle over the parts where I usualy use lineTo(). I guess this would speed things up alot, but this is very unflexible and hackish.
Is there anything else I can do to get the Paths rendert fast?
I already used setSmooth(false), caching is not an option as the paths get animated.
Final plattform should be Linux now developing on Mac
Thanks Robi
Currently JavaFX does all its path rendering in software and not in hardware and there is not much you can do about this especially if caching is not an option for you. The only possibility I see for you is to have a look at the 3D stuff. Maybe you can use a triangle mesh for your purposes. That's something I always wanted to try but never had the time to do :-)
I'd like to program a detection of a rectangular sheet of paper which doesn't absolutely need to be perfectly straight on each side as I may take a picture of it "in the air" which means the single sides of the paper might get distorted a bit.
The app (iOs and android) CamScanner does this very very good and Im wondering how this might be implemented. First of all I thought of doing:
smoothing / noise reduction
Edge detection (canny etc) OR thresholding (global / adaptive)
Hough Transformation
Detecting lines (only vertically / horizontally allowed)
Calculate the intercept point of 4 found lines
But this gives me much problems with different types of images.
And I'm wondering if there's maybe a better approach in directly detecting a rectangular-like shape in an image and if so, if maybe camscanner does implement it like this as well!?
Here are some images taken in CamScanner.
These ones are detected quite nicely even though in a) the side is distorted (but the corner still gets shown in the overlay but doesnt really fit the corner of the white paper) and in b) the background is pretty close to the actual paper but it still gets recognized correctly:
It even gets the rotated pictures correctly:
And when Im inserting some testing errors, it fails but at least detects some of the contour, but always try to detect it as a rectangle:
And here it fails completely:
I suppose in the last three examples, if it would do hough transformation, it could have detected at least two of the four sides of the rectangle.
Any ideas and tips?
Thanks a lot in advance
OpenCV framework may help your problem. Also, you can look to this document for the Android platform.
The full source code is available on Github.
So I'm making a game with my group on processing for a project and we all have different computers. The problem is we built the game on one computer, however at this point we have realized the the (1200,800) size we used does not work on our professors computer. Unfortunately we have hard coded thousands of values to fit on this resolution. Is there any way to make it fit on all computers?
From my own research I found you can use screen.width and screen.height in order to get the size of the screen, I set the game window to about half the screen size. However all the images I had loaded for background and stuff are 1200x800 So I am unsure how to go about modifying ALL of my pictures (backgrounds), and hard values.
Is there anyway to fix this without having to go manually change the 1000's of hard values? (Yes I am fully aware how bad it is I hard coded the numbers).
Any help would be greatly appreciated. As mentioned in title, the language is processing.
As I'm sure you have learned your lesson about hard-coding numbers, I won't say anything about it :)
You may have heard of embedding a processing PApplet inside a traditional java JFrame or similar. If you are okay with scaling the image that your PApplet draws (ie it draws it at the resolution that you've coded, and then the resulting image is scaled up or down to match the screen), then you could embed your papplet in a frame, capture the papplet's output to an image, scale the image, then draw it to the screen. A quick googling yielded this SO question. It may make your game look funny if the resolutions are too different, but this is a quick and dirty way. It's possible that you'll want to have this done in a separate thread, as suggested here.
Having said that, I do not recommend it. One of the best thing (IMO) of Processing is not having to mess directly with AWT/Swing. It's also a messy kludge and the "right thing to do" is just to go back and change the hard-coded numbers to variables. For your images, you can use PImage's resize(). You say your code is several hundred lines long, but in reality that isn't a huge amount-- the best thing to do is just to suck it up and be unhappy for a few hours. Good luck!
I feel like I have a very typical problem with image comparison, and my googles are not revealing answers.
I want to transmit still images of a desktop every X amount of seconds. Currently, we send a new image if the old and new differ by even one pixel. Very often only something very minor changes, like the clock or an icon, and it would be great if I could just send the changed portion to the server and update the image (way less bandwidth).
The plan I envision is to get a rectangle of an area that has changed. For instance, if the clock changed, screen capture the smallest rectangle that encompasses the changes, and send it to the server along with its (x, y) coordinate. The server will then update the old image by overlaying the rectangle at the coordinate specified.
Is there any algorithm or library that accomplishes this? I don't want it to be perfect, let's say I'll always send a single rectangle that encompasses all the changes (even if many smaller rectangles would be more efficient).
My other idea was to get a diff between the new and old images that's saved as a series of transformations. Then, I would just send the series of transformations to the server, which would then apply this to the old image to get the new image. Not sure if this is even possible, just a thought.
Any ideas? Libraries I can use?
Compare every pixel of the previous frame with every pixel of the next frame, and keep track of which pixels have changed?
Since you are only looking for a single box to encompass all the changes, you actually only need to keep track of the min-x, min-y (not necessarily from the same pixel), max-x, and max-y. Those four values will give you the edges of your rectangle.
Note that this job (comparing the two frames) should really be off-loaded to the GPU, which could do this significantly faster than the CPU.
Note also that what you are trying to do is essentially a home-grown lossless streaming video compression algorithm. Using one from an existing library would not only be much easier, but also probably much more performant.
This is from algorithms point of view. Not sure if this is easier to implement.
Basically XOR the two images and compress using any information theory algorithm (huffman coding?)
I know am very late responding but I found this question today.
I have done some analysis on Image Differencing but the code was written for java. Kindly look into the below link that may come to help
How to find rectangle of difference between two images
The code finds differences and keeps the rectangles in a Linkedlist. You can use the linkedlist that contains the Rectangles to patch the differences on to the Base Image.
Cheers !