Paint will work if that's available on the computer. As slicerwizard points out dimensions will not change (in this case), but the file I'm using in example1.jpg went from 51.7KB to 173KB and the only change noted in properties is color depth went from 24 to 32. The operation system is Windows 7 Home Premium and the supplied application Paint and Snipping tool.
Paint calls the process Resize, different name to reach the same objective.
Original file (UHFsoc.JPG) was 812 by 233 which I used in another post without resampling so I was close enough to the limits on size of picture and file it was imported as is. Example1 is the original in Paint and Example2 is the Resize original in Paint. File size went from 51.7KB to 52.0KB. In this case files size was small and acceptable, issue to address directly was horizontal and vertical picture size.
For this post both examples were in the 800 by 800 range and I picked 600 for the second value and maintained aspect ration. I then saved as JPG and imported to this post.
I tried to snip the same area in Paint so the resulting JPG for example1 and example2 would be of similar display. The blue lines under Repeater Search is the image. Notice how resizing in the lower example reduced the blue line image.
I hope this helps...
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