UPDATE IMAGES
I am assuming here that you want to change the image file from .bmp to .png.
1. Go to any image editing software and change all the images in the project folder from .bmp to .png. Please do not change the image file name just change the extension. so if you have an image with name sun.bmp change create a new file with name sun.png, in the same folder where sun.bmp is present.
2. Create a script file using the Extendscript feature provided with RoboHelp 8. I am attaching a script file which does the job for you. Please click here to download the script file [see below]
3. Download the script file on your machine. Open the project in RoboHelp 8, open Script explorer pod and import the script file you have downloaded.
4. Select the script file and click on run or right click script file and select run.
5. The script file will read all the topics and snippet files present in your project and read the image tag. if there is an image file with .bmp extension, it will change that image file extension to .png and update the topic file.
6. You are done with updating your project with new image extensions.
Forum thread: http://forums.adobe.com/message/2015385#2015385
Script download: https://acrobat.com/#d=NVJ2v-EUQGqNSBn-4XeEbA
