App: batchDPI
Developer: Jiulong Zhao
Genres: Bildung, Grafik und Design

The default DPI of the macOS system is 72dpi, Microsoft Windows is 96dpi, your camera takes photos at maybe 350dpi, your scanned photo has a DPI of 600dpi, your PhotoShop was set to 100dpi …

Although the difference in DPI will not affect the quality of your picture unless you print them, it does bring some unexpected and quite messy issues when you work with pictures with different DPI.

With simple clicks, batchDPI can set all pictures in a folder to a uniform DPI you chose, no matter where they were downloaded or inputted from, or what they were edited with.

By the way, it's very interesting to find out if your favorite desktop wallpaper is originally created for Mac or PC, just check its DPI, 72dpi for Mac and 96dpi for PC. :)

Features: v1.50
- batch change thousands of pictures' DPI with a few simple clicks; 
- will copy (not replace) your photos to ensure the safety of your originals; 
- special destination folder first procedure protects against the overwrite of your original files; 
- toggle-able beep after each file processed; 
- progress indicator during processing; 
- destination folder will open automatically after processing; 
- supported formats: png, jpg, jpeg, and other format support will be added upon your feature requests;

v1.50 -> v1.52
- add support to .tif pictures upon user's feature request 
- more detailed technical support email templet 
- more detailed feature request email templet 
- updated more by the dragonBTV panel

v1.52 -> v1.80
- fully re-coded Sandbox ARC version for macOS Sierra 10.12
- updated to macOS Sierra 10.12 and still compatible with OS10.7 and above
- interface adjusted
- all deprecated function is replaced
- all file operation is changed to Sandbox compatible
- app menu and dock menu rearranged
- icon modified  
- change the color of all popup alerts to white
- alert for destination (output) folder selection modified with detailed explaining 
- the option "beep after each file" deleted for faster conversion
- More apps by dragonBTV are simplified by displaying in App Store directly

v1.80 -> v1.81
- menu rearranged
- performance improvements for macOS 10.13 High Sierra

v1.81 - v2.00
- Any Mac (Apple Silicon, Intel) version for macOS Big Sur
- new core for faster conversion
- interface fine-tuning for dark mode
- support menu updated
- fix background issue on dark mode
- new startup tip alert added
- all deprecated functions rewritten

v2.00 -> v2.06
- source folder selection alert added
- interface more compact
- all deprecated code rewritten
- More by dragonBTV menu updated

Q&A:
Q: When batchDPI finishes conversion and takes me to the output folder, all the pictures look the same as before.
A: You may not notice the change with your eyes, the app changes the picture's DPI only. You may click the 'Show Inspector' from your app 'Preview' before and after converting to see the change in your picture's DPI.

Release notes:
v2.00 -> v2.06
- source folder selection alert added
- interface more compact
- all deprecated code rewritten
- More by dragonBTV menu updated