Consider there are many free tools and utilities offer the ability to do so,however I would suggest that one most simple and effectively is FastStone Photo Resizer
FastStone Photo Resizer is a freeware download and without risk and hidden ads.
The feature is batch convert and rename processing.
What is batch Processing.
Think in a simple way
you have 100 picture with various extension and name ,then you want to have all of them the same extension and Preset of name ,so image software with ability of batch processing is your choice.
By download and using FastStone Photo Resizer is your best solution
as a step by step below.
To download FastStone Photo Resizer
UIFor a step of download and install I would skip.
But open the tool after download and install.
Tow mail function on the top menu.
So select which one you want to
Click on tiny 3 dots to look for the folder which contents your picture on your hard disk computer.
Click on icon view for list display or thumbnail
Look in the middle
Click Add select one by one picture.
Add All bring all in the folder
Looking down a bit
Output Format drop down menu list for new extension like jpg,tiff,bmp,png etc.
Output Folder : Typing the target folder name like D:\image
Select option Rename also if you want to rename and convert simultaneously with preset name or you can type in by yourself for instance image####
ReportAfter config and hit ปุ่ม Convert
you supposed to get the work done report as below.
Previous ext. was .Tif
New etx. is .jpg
Compare the images size would notice that .jpg is mach small in size than .tiff
That a basic tool and we can do more with this tool such as resize, crop, rotate, change color depth, add text and watermarks to images in a quick and easy batch mode. Drag and Drop mouse operation is well supported.