I've been researching the BufferedImage class to use for game programming purposes (so that I can make image maps for levels and use getRGB() to identify the tile in each pixel), but I'm very confused about how to actually make a BufferedImage. What's got me particularly confused is how you can't make a BufferedImage using an Image as a parameter. Step by step, how does one instantiate a BufferedImage for a simple image file (e.g. a .jpg)?
Simple steps - ImageIO.read(File file) as shown in the documentation
You can load an image with ImageIO.read(new File("example.jpg"));
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When attemting to make a simple application which uses an image I was amazed at the large number of image types available to me. I did a search on them and whilst finding a little about them cannot work out what image is ment to be used in what circumstances.
The types of image I am confused about are Image, ImageIcon, and ImageIO.
The only one of those that is an image is Image. A more powerful sub-class of Image is BufferedImage.
An ImageIcon is an image based Icon.
ImageIO simply helps us to read and write images, and do other things with images.
Be sure to check the JavaDocs for each. It adds more details.
Image | BufferedImage | ImageIcon | ImageIO
There are various ways of reading an image file in java such as BufferedImage and ImageIcon to name a few. I want to know what is the difference between these cases? Are they context dependent that in a particular case only one of them can be used?
What would be the best way of reading a image selected by JFileChooser by the user and separating the color channels of an image?
A good way is to use the different ImageIO.read methods, which return BufferedImage objects.
Image is an abstract class, so I think the real question is which subclass is more efficient for your program. Use VolatileImage if you need hardware acceleration. More on that here.
ImageIcon (and Toolkit#createImage/Toolkit#getImage) use a background loading process. That is, after you call these methods, they will return immediately, having created a background thread to actually load the image data.
These were/are used when loading large images across slow connections, like ye old 28k modems (ah, how I remember the days). This means that your application can continue running while the images are been downloaded.
You'll find in the Graphics class the drawImage methods accept an ImageObserver interface and that java.awt.Component implements this interface, this allows components the ability to automatically update themselves once the image has actually finished loading.
ImageIO on the other hand will not return until the image is fully loaded. It also makes it easier to introduce new readers/writers, making the API far more flexible then the original API. ImageIO also supports a wider range of images out of the box.
BufferedImage is also a far more flexible image class, especially when it comes to apply effects to the image.
Now, I, personally, prefer ImageIO. If I know I'm loading large images or images over a potentially slow connection, I will create my own background thread to load them. While a little more complicated, the trade offs greatly out weight the small amount of extra work -IMHO
What would be the best way of reading a image selected by JFileChooser by the user and separating the color channels of an image?
ImageIO without a doubt. In order to do any serious manipulation of an image loaded using something ImageIcon, you'd have to convert that image to a BufferedImage anyway
Whenever dealing with the loading and rendering of images in Java, I have previously always used BufferedImages to store and manipulate the images in memory.
However, I have recently come across a few different sites that use the Image class instead of BufferedImage and this got me wondering - what are the differences?
I'm aware that a BufferedImage has a larger/optimised toolset, but does come at any cost? If so, when does this cost become noticeable? In which situations would you use an Image over a BufferedImage, or vice-versa?
BufferedImage extends Image. Image is just a base abstract class and you can't instantiate it. Under the hood you are using BufferedImage or another implementation for sure.
There shouldn't be any real performance difference between directly creating a BufferedImage and a Toolkit image (java.awt.Toolkit or Image#getScaledInstance). You'll never have an actual instance of Image because it's an abstract class; you'll only be dealing with its subclasses (e.g. BufferedImage).
I am trying to create a chess game for java using images my classmate and I are working on. We are using a created image to serve as the board and pieces to place about that the user can drag and place. Unfortunately we do not currently know how to import images from a file directory into the program itself. Not only that, but we are completely clueless as to why this would occur, as the Java API guide does not clearly explain this process.
The portion of the JDK API that provides image input is the package javax.imageio. The easiest way to load an image (into a BufferedImage object) is:
BufferedImage img = ImageIO.read( new File(pathname) );
Don't forget to catch the appropriate exceptions.
Read the section from the Swing tutorial on How to Use Icons for working examples of different ways to read images and display them on a label. Its easier to drag a label around the screen then just and image.
I need to translate colors in bitmap loaded to BufferedImage from RGB to YCbCr (luminance and 2 channels chrominance) and back after process.
I made it with functions used like rgb2ycbcr() in main method for each pixel, but it isn't so smart solution. I should use ColorSpace and ColorModel classes to get BufferedImage with correct color space. It would be more flexible method, but I don't know how to do that.
I'm lost and I need some tips. Can somebody help me?
As I understood your question, you want to do the following:
Load RGB image -> process YCbCr image -> Use RGB image again
And you want us to help you, to make this process as seamless as possible. First and foremost you want us to give you a simple way to avoid the -> (converting) parts.
Well I looked into the BufferedImage documentation. It seems, as if there doesn't exist a way to change the ColorSpace of an once created BufferedImage.
You could create a new BufferedImage with an YCbCr color space for that you can use the predefined ICC_ColorSpace. Then you copy the data from your old image possibly via ColorSpace.fromRGB to the YCbCr color space, do the image processing and then convert again via ColorSpace.toRGB. This method requires you to fully convert the image before and after processing via existing methods. Furthermore you have to know, how ICC_ColorSpace converts your image to YCbCr color space. Otherwise you can't know, which array indices corresponds to the same pixel.
If you just want to create a wrapper around the RGB-BufferedImage that lets you manipulate this image, as if it was an YCbCr image, that isn't possible with BufferedImage.
EDIT:
To convert the color space of a BufferedImage use ColorConvertOp. The code would look something like this:
ColorConvertOp cco = new ColorConvertOp(new YCbCrColorSpace(), null);
BufferedImage ycbcrImage = cco.filter( oldRGBImage, null );
This requires you to either write your own ColorSpace class or you could download and use the classes mentioned here. If you just want to load a JPEG image you should use the predefined classes.