From a credits roll video file like this:
https://i.stack.imgur.com/VM0SG.gif
How can I extract unique frames with ffmpeg? With unique frames I mean next image should start where exactly previous one ended.
Main goal is to then combine them together into one image file which I already know how to do with vstack filter. But extracting the required images is the problem.
Thanks.
Related
I kind of reverse engineered an image filter. Actually it was just a pixel by pixel operation so I applied it over different images and by comparing each pixel of original image and filtered image (using PIL) I now know what RGB value from original image became what RGB in the filtered image. For example like RGB(0,0,1) became RGB(2,3,81) (suppose) etc and I know this for all 16,777,216 colors.
If what I did is correct then my question is how can I create a filter out of this data that can be used in flutter apps. One option is to use conditional statements but that's just theoretical as I'll have to manually write 16,777,216 statements just for this one filter. So is there any software or program or code or anything else that I can use to create a filter out of this data that can be used in flutter apps. This is important because ultimately I want to use this filter in my flutter app.
Any help would be much appreciated.
Thank you very much.
I have lots of high resolution image files that have regions of colors, basically blobs with different rgb values. I need to go through the images and for every image make a text file that contains the coordinates to one pixel in every blob. Because I have so many files the script needs to be fast. I already wrote some scala code to do the task except it only saves locations for one blob per specific RGB value, meaning if I have two blobs of the same color that are not connected it will only save one the location for the first one found. The solution to this is for each images copy the location and colors to a map and when I find a blob flood delete (flood fill except delete instead of fill) and then keep parsing on the new map. However, I think this will make run time horribly slow because I will have to go through the entire image to add it to a map before even starting the parse. Thoughts? Am I going about this all wrong?
Thanks.
I have a sequence of images to be converted into a movie. The only problem is that, I wanted to start converting image number 120 until 240 into a movie using ffmpeg but I don't know the command line for that. Is there any possible command line for this kind of case?
I grabbed frames using php-ffmpeg api and then converted it into move. Here is a sample code which shows how to grab frames
#$mov = new ffmpeg_movie($video_file_name);
if($mov->getFrameCount() > 1000) {
//grab frames and make movie
}
i'm about to developp a memory game for children like,i have 6 different images show in in random order in 12 places. note(each image show twice) and i want to know how to set images randomly and how to mach UIImage with animation? any help..
Have a look at the answer by Kristopher at What's the Best Way to Shuffle an NSMutableArray?. You can create an array of 12 images (each repeated twice) & then shuffle the array. Then display the images in the order obtained after shuffling.
Regarding animations, you first need to at least visualize what animation you want. People can then help you achieve that.
HTH,
Akshay
There is an app on the app store called active photo (http://itunes.apple.com/us/app/active-photo/id366798464?mt=8) that allows you to embed a hidden image or .exe file inside of an image. I would like to know how to do this regrading adding images to images, kinda like sub images in the original image.
I've been looking into metadata but no tag seems to be big enough to hold an NSData representation of the second picture.
How would one go about adding any type of file to an image, either through embedding or metadata, that would allow the image to be sent though email and or text message and still retain the data?
Thank you.
This is known as steganography.
I would imagine the simplest way of hiding a file inside a JPEG image is just to alter its pixel data in such a way that the compression doesn't damage it but is subtle enough that an interceptor can't detect the hidden data.
I don't think it is possible with JPEG because it's a lossy compression so you would end up corrupting the embedded file. But PNG uses a compression method similar to Deflate, which is loseless.
I have started writing a program like this. The idea was to hide bytes of data by splitting them into the least significant bits of pixels' color channels. Let me do some examples.
An RGB-8 image represents a pixel with 3 bytes, one for red, one for green and one for blue. I store 3 bits into red channel, two into green (human eye is more sensitive to green color) and 3 into blue. So I embed one byte per pixel. Similarly with RGBA-8 image I do 2-2-2-2. This of course involves some bitwise operations.
Things become more interesting with RGB(A)-16 images, where there are two bytes per channel. I use the entire least significant byte of every channel with minimal distortion (worst case 255 / 65535 = ~3.9%) and store up to 3 or 4 bytes of data per pixel. Not bad!!
Moreover there are no complex bitwise operations in this case, a single assignement does the job.
There are lot of improvement to it. I thought to ask the user a password, hash it and seed a secure pseudo random number generator, then no longer move pixel by pixel but instead asking the generator for a new random index.
The drawback of this solution is that the more data has already been embedded, the slower it becomes, because the generator will give more and more occupied indices. But it is much more secure in this way. To make it even more safer I thought to introduce noise data in the untouched pixels, in order to hide the positions of the true data.
As you can see you can do a lot with PNG images! If you are interested I can give the code I wrote so far.