Is it possible to convert excel files to an image file such as jpg?

Search the internet for free screen capture software.
Many have various capture options (screen, region, window, etc)
and output options (jpg, bmp, etc)

I hope that helps.

With MS Windows OS,
1. Use Alt+Print Screen to capture the active window, use Paint to paste it and save as jpg or bmp, etc.

2. Use Ctrl+Print Screen to capture the entire screen, including all windows and wallpaper that might be showing.
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Using Alt/Ctrl + Print Screen copies the image to Windows Clipboard and it can be pasted into any application (e.g. MS Word)