I am interested in to how change hue of the texture in efficient way ? I am experimenting to create space dust which will change it's color every few seconds with nice, smooth transition from one color to another.
I find this possible in few ways:
Using core image like in this example. But I don't know how will this work in combination with Spritekit...
Using particle emitters to create space dust and change color of particles over time using particleColorSequnece property.
And easy one that came up on my mind , while playing with Photoshop, which is using two same, but differently colored images, one over another, and changing the opacity of the topmost one.
This gives me the effect I want, and actually looks fabulous, but is there any better way ? Maybe using SKTexture? In this particular case, I just need to change from one color to another , but what would be an efficient way to do this when multiple changes are required one after another ? This way, my third example requires additional images...
Here is the link which most closely describe what I am trying to accomplish. Just look how space dust changes its color overtime(from dark blue to purple and later to green or orange). I suppose this is done programatically... I would like to ask moderators to remove a link if it is not suitable to post it here. Thanks!
It is kind of a hard questions to answer and is rather subjective, however...
I personally would do the Emitter Node approach, because it seems like it is built for the type of use you are looking for and could have some cool effects trailing behind.
With that being said you specifically asked about changing the hue and colorBlendFactor might be what you are really looking for. I don't have a great link for it, but this might get you pointed in the right direction. You can see how they are blending colors to get the desired result.
Your solution with changing the alpha of two separate colors doesn't sound like a bad approach either.
Hopefully that helps and good luck =)
Related
I am working on project in C#/Emgu CV, but answer in any language with OpenCv should be ok.
I have following image: http://i42.tinypic.com/2z89h5g.jpg
Or it might look like this: http://i43.tinypic.com/122iwsk.jpg
I am trying to do automatic calibration and I would like to know how to find corners of the field. They are marked by LEDs, but I would prefer to find it by color tags. If need I can replace all tags by same color tags. (Note that light in room is changing so the colors might be bit different next time)
Edge detection might be ok too, but I am afraid that I would not find the corner correctly.
Please help.
Thank you.
Edit:
Thanks aardvarkk for advice, but I think I need to give you little bit more info.
I am already able to detect and identify robots in field and get their position and rotation. But for that I have to set corners of field manually first. So I was looking for aa automatic way, but I was worried I would not be able to distinguish color tags from background because light in the room is changing quite often.
And as for the camera angle. Point of this is that camera can be every time from different (reasonable) angle.
I would start by searching for the colours. The LEDs won't be much help to you as they're not much brighter than anything else in the scene. I would look for the rectangular pieces of coloured tape. Try segmenting the image based on colour. That may allow you to retrieve the corner tape pieces directly without needing to know their exact colour in advance. After that, you may look for pairs of the same colour blob that are close to each other to define the corners where the pieces of tape are the same. Knowing what kinds of camera angles you are going to have to solve is also very important -- if you need this to work when viewing from the side, then this approach certainly won't work. If it's almost top down, this would probably be a good start. Nobody will be able to provide you with a start to finish solution, but this might be a good base to begin with.
What I basically need to achieve is a Fruit Ninja - style "slash" effect, where the "slash" trails the user's touch and follows the shape of the user's gesture, and is thinner the longer the distance the user has swiped.
The simplest way to achieve this seemed to be to collect all the points the user passes through in a UIBezierPath, and "stretch" an image through the length of the BezierPath. This would achieve the kind of "trailing" effect I was looking for and also ensure that the line is thinner if the distance travelled is longer.
However I can't seem to find a way to actually implement this. Is this even possible?
Alternatives? Thanks.
P.S: This is for a low-medium priority section of a regular app and not a game, so I would like to avoid having go down to OpenGL and spend a lot of time to achieve this (with completely custom drawing, etc). Something at the SDK level would be preferred, and if that's not possible at all, we'll just figure out a different UI.
Thanks!
For pretty easy-to-use stretching teqhniques of images/views you could look into
https://github.com/hfossli/AGGeometryKit/
I recommend trying to draw using CoreGraphics. See this link
http://www.effectiveui.com/blog/2011/12/02/how-to-build-a-simple-painting-app-for-ios/
Okay. Maybe you can use this.
https://github.com/hfossli/AGDraw
Just something I wrote a while ago. Hit clear and try to draw something (clear will toggle between two types of strokes). You'll see the width of the penstroke will increase with the velocity you use.. I guess that fits your need. If you fix some bugs, please make a pull request. You are free to use the code, but I will add a MIT license later.
I want to replace the particular color of an image with other user selected color. While replacing color of image, I want to maintain the gradient effect of that original color. for example see the attached images.
I have tried to do so with CoreGraphics & I got success to replace color. But the replacing color do not maintain the gradient effect of the original color in the image.
Can someone help me on this? Is the CoreGraphics is right way to do this?
Thanks in advance.
After some struggling almost with the same problem (but with NSImage), made a category for replacing colors in NSImage which uses ColorCube CIFilter.
https://github.com/braginets/NSImage-replace-color
inspired by this code for UIImage (also uses CIColorCube):
https://github.com/vhbit/ColorCubeSample
I do a lot of color transfer/blend/replacement/swapping between images in my projects and have found the following publications very useful, both by Erik Reinhard:
Color Transfer Between Images
Real-Time Color Blending of Rendered and Captured Video
Unfortunately I can't post any source code (or images) right now because the results are being submitted to an upcoming conference, but I have implemented variations of the above algorithms with very pleasing results. I'm sure with some tweaks (and a bit of patience) you might be able to get what you're after!
EDIT:
Furthermore, the real challenge will lie in separating the different picture elements (e.g. isolating the wall). This is not unlike Photoshop's magic wand tool which obviously requires a lot of processing power and complex algorithms (and is still not perfect).
let's say I want to display a customizable (2D, cartoon-like) character, where some properties e.g. eye color, hair style, clothing etc can be chosen from a predefined set of options. Now I want to animate the character. What's the best way to deal with the customization?
1) For example, I could make a sprite sheet for each combination of properties. That's not very memory efficient and not very flexible, but probably gives the best performance.
2) I could compose the character from various layers, where each property only affects one layer. Thus, I could make a sprite-sheet for the body, a collection of sprite-sheets for the eyes (one for each eye color) etc.
2a) In that case, I could merge the selected sprite-sheets in order to generate a single sprite-sheet containing the animation of the customized character.
2b) Alternatively, I could keep the sprite-sheets separate and try to animate them simultaneously as layers. I fear, that this might become a problem performance-wise.
3) I could try to modify the layers programmatically, e.g. use a sprite-sheet for the eyes as a mask and map some texture on it before merging it down to a single sprite-sheet. I would think this is a very flexible approach when it comes to simple properties like eye colors, but might become difficult for things like hair-style. I am aware that this depends much on the character and probably a general answer is difficult.
I assume that my problem is not new, so there is probably a standard approach to it.
Concerning the platform, I'm particularly interested in iOS and try to avoid OpenGL (well, I'm open-minded). Maybe there is a nice framework that can help me here?
Thanks!
Depending on what your working on, you might want to animate part/all of the animations outside in another tool, such as flash. It is much easier to work with a visual environment.
Then there are tools that take swf files, and create sprite sheets that you would then animate in cocos2d.
That is a common game creation workflow.
You problably want to take a look on how to create sprites at cocos2d.
Cocos2d comes with a set of tools that help you to animate single parts and offers abstractions to compose parts (like CCBatchNode or CCNode). Also, it comes with tools that helps you to pack sprites into sprite sheets (e.g Texture Packer) and develop levels (e.g Level Helper).
Cocos2d is an open source framework and it is widely used. You also have cocos3d but I never used it :).
I am creating an app at the moment which take a picture of a person's face and I want to change the colour of their skin (just for fun!)
I have a piece of code that runs through the image pixel by pixel and finds the skin colour and then amends it to a new colour, which kind of works, but even though I am allowing for the differences in tones and adjusting the new colour in the same way it is still very hit and miss.
can anyone point me in the right direction?? is it even possible? I dont really want to use a filter as I dont think it would give the right effect.
Thanks
You should look at some computer vision techniques such as segmentation and feature extraction.