The first image editing program that almost all the Windows users become familiar is perhaps the Microsoft Paint. I myself started out playing with Microsoft Paint a long time ago when I was still in high school. But pretty soon I found out that there other actually other third party image editors with much more functions and features. This is when I first found out about FastStone Image Viewer and it has become my favorite image viewer since then. The developers of FastStone Image Viewer also have created another software called FastStone Photo Resizer and it is available for free.
FastStone Photo Resizer, as anybody can easily guess, specializes in resizing and renaming the image files. It can also be used to convert the image file formats from one to another. Although these functions already exist in many different programs including IrfanView and FastStone Image Viewer, this program can help you batch process a large number of images in one shot.
The very basic use of this image processing program would be to select a number of source image files, choose an output folder, pick an image format for the output and hit the Convert button. But you can keep adding more and more functions to this basic operation. For example, you can add file renaming to the conversion. And if you do not want to convert the image file types, just want to rename them, then you can switch to the Batch Rename tab from where you can specify the filename templates to rename the files or use search-and-replace method to rename the files.
As far as image file type conversion is considered, you can add many more effects by choosing the Advanced Options. In these advanced options, you can choose to add text, resize, rotate, crop, change canvas, change color depth, change brightness/contrast/gamma/saturation, change the DPI resolution, add watermarks or border effects. Each of these effects is loaded with so many options that you can play around with them for hours.
Conclusion: FastStone Photo Resizer is a complete image conversion, resizing and renaming program that comes with all the popular effects like watermarking, rotating, borders etc. It supports all the popular image file formats and works on all the versions of Windows.
You can download FastStone Photo Resizer from http://www.faststone.org/.