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I'm trying to find a real time image processing tool that can do image resizing, image/text overlaying and format converting. I found some related posts but they don't quite answer my question.
Prioritized criteria for the tool:
The processing time needs to be less than 100 ms.
The size of output image needs to be small. It needs to convert 1 to 2 megabytes of jpeg image to around 75k.
The quality needs to be good. This is subjective. We know jpeg image conversion loses quality. I hope to find a tool that has better conversion algorithm such that the output is close to the original image.
It can be implemented in java or php.
One commonly used tool is GD library. GD library meets criteria 1 and 2. But the image quality is usually not great, which is the reason I'm still looking.
I tried ImageMagick through command line. The quality is better but the size of output image is also larger. I believe it's also slower than GD.
I wonder what real time image processing tool you'll recommend. If it's GD or ImageMagick, are there tricks to improve the overall performance?
Thank you!
I'd highly recommend graphicsmagick (http://www.graphicsmagick.org/). It's a fork of imagemagick with more of a focus on performance.
There are also tricks to getting imageMagick/gm to produce smaller images - for example you can strip the colour profiles from the images you create, eg:
gm mogrify -resize 180x180 -quality 75 +profile "*" image.jpg
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Sorry if this has been addressed before, I searched it up and I couldn't seem to find a question like this. I am making a social media app, and I want to preserve the quality of the images as much as possible. To make a data representation of the image I am using "UIImageJPEGRepresentation" and I would like to know what an optimal setting for the compression quality is.
One big consequence of setting the quality below 1 is that the image uploads to my server in much less time. I have experimented with the compression and to me I can't really tell the difference between 0.6 and 1 unless I zoom in on a computer, but I just wanted to know if there was a number or range that would produce favorable results.
One of the interesting and evolving format is Webp format that Google has introduced. This article suggests that Facebook is also trying to use this format. To answer the exact question as to how much to compress please note the following:
-Format of the image(I assume yours is JPEG)
-Compression technique(Lossy or Lossless)
-Target devices(I assume yours is mobile)
Considering above parameters(and more) and looking at the dimensions of all social networking sites I suggest you to get the compression level high enough such that you can see a difference in the image quality on the computer, that way you would have found an optimal level, remember lower the better till it degrades. Additionally you can find the information at this.
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I am currently working on a project where I have to extract the facial expression of a user (only one user at a time from a webcam) like sad or happy.
There are a lot of programs/APIs to do face detection but I did not find any one to do automatic expression recognition.
The best possibility I found so far:
I used OpenCV for face detection earlier, which was working great, so If anyone has some tips on how to do it with OpenCV, that would be great!
Some user on a OpenCV board suggested looking for AAM (active apereance models) and ASM (active shape models), but all I found were papers.
-So i'm Using Active Shape Models with Stasm, which will give me access to 77 different points within the face, so I would still have to manually map them to expressions.
Any programming language is welcome.
After 2.4 release, opencv came with a face recognition API. You may define sad and happy faces as two different faces and use the API to classify them. If you are looking for any tutorials you can check out opencv's tutorial page, too.
Maybe this article can help you.
It is explanation of concepts used to achieve result shown here:
Also, you might want to have a look here.
All of above mentioned is a work of people who more or less achieved what you watn.
I want to do same as you - facial expression recognition with OpenCV, so I hope sooner or later we can exchange our ideas.
Half the problem is solved for you using OpenCV. If you built OpenCV with examples, you can run an example named c-example-smiledetect which can detect a smiling face with different levels.
The code should be in you OpenCV folder under samples/c. i recall you can adjust the sensitivity in the code so that might help. You can also find the code here.
On another note, an implementation of AAM using OpenCV can be found in this book (chapter 7). This doesn't include the searching and fitting part though, just shows how to create an AAM from ASM and a texture.
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I would like to use a plotting tool to visualize data for image processing. What is a good (free) tool?
gnuplot worked very well for me when I was working on some performance analysis. Easy to create datasets and it will plot multiple items against the same "time" base (as I was using it)
The one I like the most is Incanter based on Clojure.
The most recognized would maybe be R
Both are very good and free.
gnuplot works well for me. it is freely downloadable at sourceforge and here is the link for gnuplot related stuff
http://www.gnuplot.info/
I often export data to plot as csv, and then use ms excel or gnumeric, or other spreadsheet programs to read that and make a quick plot. quite handy for small (< 65535) set of data. :-)
Depends on the type of "plotting" you want to do - I use Matlab and find its plotting excellent for image analysis, particularly using imshow and surf. As you requested a free tool you could use Octave (an open source clone of Matlab) and its image processing library to do similar.
MathGL (and its front-end UDAV) is free (GPL, and partially LGPL) plotting library. It have more than 55 general types of graphics for 1d, 2d and 3d data arrays. It can export graphics to raster and vector (EPS or SVG) formats. It has Qt, FLTK, OpenGL interfaces and can be used even from console programs. It has functions for data handling and script MGL language for simplification of data plotting. Also it has several types of transparency and smoothed lightning, vector fonts and TeX-like symbol parsing, arbitrary curvilinear coordinate system and many over useful things. It can be used from code written on C++/C/Fortran/Python/Octave and many other languages. Finally it is platform independent and free (under GPL v.2.0 or later license).
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I need collection of sample images (negative images, or also called background images)
for haar training using opencv. It is written that I need to have a lot of them. About 5000 or 10000. Do you know where to get them?
This site have some haar negatives from various databases. You can download by svn: svn co http://tutorial-haartraining.googlecode.com/svn/trunk/data/negatives/
UPDATE: It is possible that the repository died, so you can go to GitHub. I found one that was exported automatically from google code here.
you can find it anywhere especially in google.. negative images are just images that does not contain your positive images/samples which is the object of interest.. anything that doesn't contain your object of interest can be a negative samples..
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I have a batch of PNG files that I need to convert to JPEG. I'm looking for a free trustworthy utility that will give me the most optimal possible JPEGs.
I've found some paid utilities and i HAVE Photoshop, but I want something dedicated that is made for the task and I dont want to accidentally download spy ware.
I'm really surprised not to find this question already on StackOverflow, but please point me in the direction of any similar questions if they exist.
One word: ImageMagick.
Not sure about if it generates the absolute smallest JPEGs you can get, but it's certainly good and would be my first choice.
IrfanView is another option. It has a "Batch Convert/Rename" feature, but it's a Windows-only GUI app.
Imagemagick (http://www.imagemagick.org/script/index.php) can do batch conversion of images.
mogrify -format jpg *.png <= Converts all png files to jpg
The ImageMagick convert utility should do everything you require. There are a number of options which you can use to control the JPEG output quality.