Image darker when saved than on-screen buffered image

Question

Hi,
Here is my little application. I am trying to simulate an rgb screen look based on image data. ie, the new image is an exaggerated tv look of the original image.
When I try to encode/save a jpeg from my buffered image, the saved image is darker (colours also seem to be different) than what i see in my application frame. I like what I see in the JFrame and would like to have that saved. I am just an artist hack so excuse the cobbled together code. I have also included the original image, the image as it is saved, and an image as a rough approximation of the image in the JFrame.
In the code you will see I have tried different ways to encode the image (commented out)
Any ideas about this issue or how to make this program more sound please let me know.
the code:
http://zukanter.com/javaImageTest/displayImageRGBBuffer.java
the orignal loaded into the appp:
http://zukanter.com/javaImageTest/myPic.jpg
the saved image:
http://zukanter.com/javaImageTest/_003.jpeg
the image as it is in the application window:
http://zukanter.com/javaImageTest/_003Screen.jpg

Answer 1

Hi
My 2c.
I`ve had a quick look at your code and the output and I`m assuming that the vertical RGB lines are what you intended.
Jpeg works in blocks, and averages pixel valiues across them.
If introducing those primaries into the graphic and then compressing it makes it darker that`s likely the result of the primary colours being averaged by the compression algorithm.
You should look at resizing the image first, drawing it onto an offscreen buffer, then doing an overlay (alpha channel) with the primary colors instead, IMHO.
regards