Although I have found a lot about converting PNG to GIF for various languages and platforms, interestingly there are very few things to convert GIF to PNG with C++. I am rendering GIF images by using mimeTeX and want to draw them to my PDF by using libharu. The problem is that neither mimeTeX can render PNG, nor libharu can draw GIF. I know really limited things about both formats (just some elementary things I read from official PNG website and Wikipedia) and thus cannot convert GIF to PNG. I am very sorry that I cannot show you what I have tried because I could not find a start point. Please also note that all images will be created at runtime. I can use any kind of library that will work on Windows 7; and since my code is already excessively complex, I really do not want to make it even more complex. If a simple trick exist for this specific job, it will be highly appreciated. Thanks for that.
ImageMagick is the way to go; there's even a C++ library: http://www.imagemagick.org/script/magick++.php
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Need help with an interesting task. I need to write a C++ program that builds the graph and save a graphic file format bmp. I know how to initialize the bmp, but how to build a graph in it , I can`t think up. Necessary practical and theoretical help if there is a link to an article on the subject.
P.S. I apologize for my bad English :I
There are a lot of ways to do graphics in Windows. The lowest level and most fundamental is to use the Win32 APIs that employ the GDI (Graphics Device Interface), which is built in to Windows. With GDI calls you can paint anything to the screen, and the same GDI calls can be used to paint on an in-memory bitmap that is off screen. To get started in this direction search the net for Win32 tutorials.
I recommend FreeImage library (http://freeimage.sourceforge.net/) it's simple and fast lib without additional problems, you can manipulate graphic files dealing with them like 2D array.
And also, they have nice PDF document about API, you don't need tutorials to use it, just read API and you will get it. Also pr0tip: DON'T PUT SPACES BEFORE SPECIAL CHARACTERS LIKE ",!?.".
You might want to take a look at the graphviz package.
Since a few days im working on a tool where i need to draw textures on several file format with directX 11. After googling a lot, i didnt found how to do.
I'm using D3DX11CreateShaderResourceViewFromFile for load .dds and .png files, but i read somewhere else that .tga isn't supported anymore. I read something too about D3DLOCKED_RECT to set each pixels of the texture, and read .tga files to know these pixels, but that was for directX 9.
Any help or tips? Thanks in advance.
//note: I don't use D3D11
MSDN page for D3DX11CreateShaderResourceViewFromFile says there is DirectXTex library, that should be able to load *.tga files using LoadFromTGAFile routine. You should give it a try. If it doesn't work for you, you'll have to write your own texture loader. (because it was possible to make your loader for textures in D3D9, it should be possible to do the same thing in D3D11). *.tga format is documented somewhere and many beginner tutorials specifically deal with loading this particular format without 3rd party libraries.
Two advices:
Next time, when in doubt, read documentation.
DON'T look at *.png format. This format loads very slowly (jpeg is faster, uncompressed bmp is faster, dds is faster) and most likely isn't suitable for games that need to load many images often (it is okay to use it for start menu, ending screen, etc). Either use uncompressed format (such as *.tga) or (since you're using directx) use *.dds format. Your images most likely will take extra disk space, but will load more quickly.
I'm just curious if there is a way to use OpenGL to write pixel data to an external JPEG/PNG/some other image file type (and also create an image to write the data to if one does not already exist). I couldn't really find anything on the subject. My program doesn't really make use of openGL at all otherwise, I just need something that can write out images.
Every image "put into" or "taken from" OpenGL is in a rather raw pixel format. OpenGL does neither have functionality for file I/O nor for handling of sophisticated image formats like e.g. BMP, JPEG or PNG, as that is completely out of its scope. So you will have to look for a different library to manage that and if this was the only reason you considered OpenGL, then you don't need it at all.
A very simple and easy to use one (and with an interface similar to OpenGL) would be DevIL. But many other larger frameworks for more complex tasks, like Qt (GUI and OS) or OpenCV (image processing) have functionality for image loading and saving. And last but not least many of the individual formats, like JPEG or PNG usually also have small official open-source libraries for handling their respective files.
Is this possible? It doesn't matter what format the image is, but I have to be able to open it, read pixel data into some sort of array, create a new image using a modified set of pixel data.
Thanks!
Boost.GIL has a good video tutorial which shows you how to read/write and process raw image data in a very generic, yet efficient, way.
You need code to encode and decode the formats you want to support. You can do this yourself (not really ideal/practical,) you can embed encoding/decoding libraries (like libpng, for example,) or you can embed image libraries like DevIL.
Boost seems to include some sort of image access library known as Boost.GIL. I really don't know much about it, though.
I suggest the TARGA image format for your needs. You just read/write a few values in a header, then the rest is an uncompressed array of RGBA pixel data. You won't even need Boost!
I suggest CImg. This library is extremely easy to use. You only have to include a header file in your code and set some parameters when compiling and that's it! I've used CImg with MingW and GCC.
I'm working on a game, and all of my graphics use magenta as transparent/magic color.
They are all 32-bit and the magenta is just for conveniency.
Anyway, I would appreciate if someone could advice me what library should I use to load my images (I need to load them in GL_RGBA format, both internal and texture specific).
If only PNG support is necessary, use libpng. DevIL is supposed to be easy, but it's somewhat bloated (does a lot more than just load images) and internally actually calls OpenGL functions which can mess with your own OpenGL logic.
I personally prefer SDL_image, since I'm using SDL in my projects anyway. While not immediately obvious, SDL_BlitSurface() function can do the conversion from whatever IMG_Load() returns to the necessary pixel format.
DevIL can load virtually every file format and can directly create OpenGL textures. It is the easiest way to go.
You should also use a file format which supports an alpha channel (PNG, TGA, ...). Using a "magic color" in 32-bit images is really out-dated!
Apart from the other answers mentioning SDL and DevIL, there are two more options to consider:
Use libpng directly. This will probably have the smallest impact on the code size if that matters, since you get no bloat for other formats you're not using, no DLLs, etc.
Use operating-system texture loading. This can be a nice way to reduce dependencies if you prefer using OS features over external libraries. GDI+ in Windows XP and up has built-in texture loading for a few formats like PNG and JPEG, and I don't know for certain, but other OSs might have similar features. It's pretty simple to hook GDI+ up in to OpenGL and then the OS is taking care of your texture loading!
There is a very minimalist one file example of loading a png into openGL here:
http://tfc.duke.free.fr/coding/src/png.c
Another option is OpenCV.
It does a lot more than just texture loading, but odds are good you'll find use of its other features as well.