Introduction

JPEG Imager is an interactive image compressor with multiple additional functions.

At first, we created it to help users to reach an optimal performance of JPEG compression algorithm. It is known that the JPEG format uses so-called "lossy" compression. This means that to achieve high compression ratio it is necessary to truncate some of original image information. Due to this, full restoration of the original image without visual noise (called "artifacts") becomes impossible.

In practice, however, not everything is so gloom. JPEG algorithm has been built with regard to human's eye functionality and omits only that information which reflects to details most unimportant for our sight. It is possible to control the amount of truncated data - this way, you can control the volume of visual deterioration. In fact, that deterioration may be practically imperceptible even with compression ratio about 10-15 times.

It is important to know that the result you get is strongly dependant on the given image's characteristics. Different images yield different compression for the same algorithm parameters and compression noise at them looks differently. That's why when you saved images to some "lossy" format such as JPEG, you often must have been encountering a problem of choosing of optimal compression parameters. What settings to use to get the best file size, preserving acceptable image quality? These two things (size and quality) are so inter-dependent, that when you gain in one you always lose in another.

Unfortunately, the looking for optimal settings cannot be fully automatic, because there is no objective criteria by which a program could judge visual quality loss. Optimization is always a bit of art and depends on your personal requirements and preferences. Only you can say whether an image looks perfect, good, passable or bad. To make your decision, you should at least look at the compressed image and, if possible, compare it with the original one. That's where JPEG Imager becomes necessary.

First, it offers "side by side" (or split screen) viewing mode. With it, you can see two synchronized images in the same window, supplied by a set of scrolling and zooming tools. There is also a quick swap button, which allow you to detect slightest difference in the two viewed pictures.

Second, JPEG Imager is interactive. You observe visual effect just in an instant after you change compression parameters.

Third, JPEG Imager offers more flexible compression control than many other programs. It includes ability to control quality by chrominance and luminance channels, customizing of color subsampling, post-filtering, selective extra-compression and many other things.

At first glance, the program might seem complicated, but don't worry, you don't have to be a genius to understand it. Just try to play with different settings and notice what effect occurs. If you want to, JPEG Imager can automatically select an appropriate quality parameter value for a given file size limit. We think that you will like this feature.

It's also necessary to say that JPEG Imager is found upon very fast and flawless implementation of JPEG algorithm. When we developed the product, we have given great attention to the minimization of computational inaccuracy - in particular, during RGB<->YCbCr color space transitions, which is a required stage of JPEG compression. We hope that our efforts won't go unnoticed.

In any case, the program's capabilities are not limited to JPEG standard. Starting from the version 2.0, JPEG Imager supports interactive PNG and GIF compression. Now you can choose a desired format with a single mouse click.

And finally, we cannot avoid discussing of useful additional functions. We have been trying to make JPEG Imager an all-in-one solution, which would cover all tasks of image processing, from scanner or digital camera capture, through all stages of processing, to compression and storing to a file. To achieve this aim, we included TWAIN interface support and basic image manipulation and processing functions. With JPEG Imager you can change image size, crop its edges, change contrast and brightness, adjust color balance, increase or reduce sharpness and do many other things. Look for full list of supported operations in the Features section. Almost every operation supports real-time previewing. But there is more to it. Though JPEG Imager has single-document interface, it includes group processing aids, such as Batch Wizard, which can automatically perform fixed set of operations for several images and generate a thumbnail for each one.

To summarize, let's point out that JPEG Imager is perfectly suitable when you want to prepare some images to be published on the net, or for optimizing your home photo archives. It is very simple to use and does not require any extra knowledge of image processing or compressing. Owing to full-scale interactivity, you can quickly get used to the program by experimenting, without going deep into documentation.

Authors of JPEG Imager