I am attempting to make 4bit 16 color video with an adaptive color palette. I can convert each frame into a 16 color format, but I can't find an algorithm to automatically generate a 16 color palette for each frame.
I plan to change the color palette each frame to make the most use of the 16 colors, similar to Photo Shop's algorithm of generating the best 16 or 256 colors for a GIF. Can someone show me or point me towards an algorithm I can use to generate the adaptive palettes?
I am coding my project in Java since importing images and libraries was easier in it, but I can also code in C and C++. My goal for this project is so I can play videos on a Ti84CE, which will use 4bit 16 color palette color. The video linked below is what the quality would look like.
Here is what my program can generate so far with a fixed color palette. The fixed palette is not good at matching the source video too much as most colors become grey: https://media.giphy.com/media/m20vIaWvnYoCaqqfLL/giphy.gif
I know dithering is an option, but I will implement it after I can get adaptive palettes to work.
I tried internet searching for color palette generating algorithms but all the resources lead me to PhotoShop tutorials instead of coding algorithms.
I also tried generating random colors for palettes but the results were not much better. I wouldn't want to hand pick the palettes since its too tedious.
Related
Given a color (in hex) I want to generate a set of colors that look almost exactly like the given color but are a little bit different. Is there a good way to do this other than just arbitrarily/randomly increasing or decreasing r g or b?
Thanks!
I'm not sure if you're trying to do this programmatically (Sass/Compass can do it by multiplying/dividing a percentage of the hex value), or manually.
If manual, you can use this online color palette. It has a lighten/darken scheme and displays 16 colors at a time that are nearly identical.
You can use this online tool Colorglower - Get lighter and darker shades of hex color - It's a simple tool that generates lighter and darker shades of a hex color. You can even adjust the shade percentage.
Colorglower is a free online tool to get lighter or darker shades of a hex color code. Adjust how much shade by using the percentage slider. Great reference for web designers to discover different color palettes for their projects.
I'm attempting to draw to screen with a bunch of colors that I have in YCbCr coordinates. However, all drawing libraries that I can find (Windows or cross-platform) want to specify colors in RGB and I don't want to convert and lose precision. Can anyone tell me how to do this?
Since the monitor is RGB you will have to convert the colors somewhere. If you do it yourself, or let some third party library do it for you doesn't really matter. I believe SDL lets you put YCbCr/YUV-values directly. But the colors will be converted to RGB either by software or by your graphics card on the way to the monitor.
I have a PNG-Image with alpha values and need to reduce the amount of colors. I need to have no more than 256 colors for all the colors in the image and so far everything I tried (from paint shop to leptonica, etc...) strips the image of the alpha channel and makes it unusable. Is there anything out there that does what I want ?
Edit: I do not want to use a 8-bit palette. I just need to reduce the numbers of color so that my own program can process the image.
Have you tried ImageMagick?
http://www.imagemagick.org/script/index.php
8-bit PNGs with alpha transparency will only render alpha on newer webbrowsers.
Here are some tools and website that does the conversion:
free pngquant
Adobe Fireworks
and website: http://www.8bitalpha.com/
Also, see similar question
The problem you describe is inherent in the PNG format. See the entry at Wikipedia and notice there's no entry in the color options table for Indexed & alpha. There's an ability to add an alpha value to each of the 256 colors, but typically only one palette entry will be made fully transparent and the rest will be fully opaque.
Paint Shop Pro has a couple of options for blending or simulating partial transparency in a paletted PNG - I know because I wrote it.
I am doing a project trying to simulate Google Analytic Map Overlays. Take a look at this link to see what I mean (you need to scroll down to where it says "Here is a geographical country-based visitor volume overview courtesy of Google Analytics"). The Flash mapping tool I have supports Hex Color codes (e.g. color='FFFFCC'). If I am not mistaken this is basically RGB coding?
I am looking for an algorithm where I can computationally create the color codes for a select number of shades of green.
It seems I really want HSV type calculation and not a RGB one.
I think the easiest way to accomplish this is to select a set of colors and then map then to different segments of your data. I suppose you may need more flexibility.
If you want to calculate color. You can use HSV internally, and then covert it to RGB using this algorithm:
http://www.cs.rit.edu/~ncs/color/t_convert.html
how can I see the color space of my image with openCV ?
I would like to be sure it is RGB, before to convert to another one using cvCvtColor() function
thanks
Unfortunately, OpenCV doesn't provide any sort of indication as to the color space in the IplImage structure, so if you blindly pick up an IplImage from somewhere there is just no way to know how it was encoded. Furthermore, no algorithm can definitively tell you if an image should be interpreted as HSV vs. RGB - it's all just a bunch of bytes to the machine (should this be HSV or RGB?). I recommend you wrap your IplImages in another struct (or even a C++ class with templates!) to help you keep track of this information. If you're really desperate and you're dealing only with a certain type of images (outdoor scenes, offices, faces, etc.) you could try computing some statistics on your images (e.g. build histogram statistics for natural RGB images and some for natural HSV images), and then try to classify your totally unknown image by comparing which color space your image is closer to.
txandi makes an interesting point. OpenCV has a BGR colorspace which is used by default. This is similar to the RGB colorspace except that the B and R channels are physically switched in the image. If the physical channel ordering is important to you, you will need to convert your image with this function: cvCvtColor(defaultBGR, imageRGB, CV_BGR2RGB).
As rcv said, there is no method to programmatically detect the color space by inspecting the three color channels, unless you have a priori knowledge of the image content (e.g., there is a marker in the image whose color is known). If you will be accepting images from unknown sources, you must allow the user to specify the color space of their image. A good default would be to assume RGB.
If you modify any of the pixel colors before display, and you are using a non-OpenCV viewer, you should probably use cvCvtColor(src,dst,CV_BGR2RGB) after you have finished running all of your color filters. If you are using OpenCV for the viewer or will be saving the images out to file, you should make sure they are in BGR color space.
The IplImage struct has a field named colorModel consisting of 4 chars. Unfortunately, OpenCV ignores this field. But you can use this field to keep track of different color models.
I basically split the channels and display each one to figure out the color space of the image I'm using. It may not be the best way, but it works for me.
For detailed explanation, you can refer the below link.
https://dryrungarage.wordpress.com/2018/03/11/image-processing-basics/