Version 2.5.2, 11/01/2019
	Scroll the image up and down by the arrow keys up and down if current image isn't a multi-frame image, or by Ctrl + mouse wheel if they are not used to zoom the image.
	Auto brightness and contrast updated.

Version 2.5.1, 08/17/2019
	Switch directory: maintain file index if Ctrl key is down and file count of the two directories are the same.

Version 2.5.0, 04/06/2019
	PBM/PGM/PPM file formats supported.

Version 2.4.3, 03/16/2019
	APNG: fixed bug.

Version 2.4.2, 02/17/2019
	Window title updated, seperating file name and directory name.
	Removed the annoying dialog that prompts the user when the last/first image is reached, after enabling stop on last/first image when switching images.

Version 2.4.1, 02/10/2019
	Window title updated, adding file index and total image file count in current folder.
	Settings: Stop on last/first file when switching files.
	Esc key to exit the program.

Version 2.4.0, 02/04/2019
	APNG file format supported.
	APNG -> JPEG.
	APNG -> PNG.
	File name sorting algorithm updated.

Version 2.3.0, 11/04/2018
	Improved password security.

Version 2.2.5, 08/12/2018
	Edit with Pictor: fixed the bug that the main window of Pictor is sometimes minimized instead of maximized.

Version 2.2.4, 08/12/2018
	Edit with Pictor: fixed bug with files whose file name contain spaces.

Version 2.2.3, 08/11/2018
	Move/Save file: fixed the bug that bad image files can not be moved or saved.

Version 2.2.2, 08/11/2018
	WebP images: fixed bug.

Version 2.2.1, 08/04/2018
	WebP animation playing: fixed bug.

Version 2.2.0, 08/01/2018
	WebP images and animations supported.

Version 2.1.1, 07/15/2018
	File: Save a copy of this file in another directory.
	File: Move this file to another directory.

Version 2.1.0, 07/08/2018
	File Rename: F2
	File Copy: Ctrl + C
	Warm Color: Ctrl + M
	Cold Color: Ctrl + D
	CMYK: Show CMYK in window title, if the image is CMYK. (JPEG only)

Version 2.0.0, 06/10/2018
	Edit: Edit with Pictor.

Version 1.7.5, 05/27/2018
	GIF: reduced memory usage when playing multi-frame GIF files.

Version 1.7.4, 05/19/2018
	BMP files that are disguised as JPEG file are not allowed to create EJPG or DualPhoto files.

Version 1.7.3, 05/12/2018
	File delete: fixed a bug concerning EJPG & DualPhoto.

Version 1.7.2, 05/05/2018
	Improved responsiveness with very large images when dragging the image after zooming it to 100%.

Version 1.7.1, 04/21/2018
	Resize JPEG/BMP/PNG: 
		Fixed crash when jpeg output size exceeds 65500x65500.
		User cancel improved.

Version 1.7.0, 04/06/2018
	Resize JPEG/BMP/PNG: improved.

Version 1.6.4, 04/01/2018
	Improved performance of opening very large BMP/PNG/TIFF files.
	Optimized memory management when switching large images.
	Circles for switching images or frames: shown earlier before they are effective.

Version 1.6.3, 03/18/2018
	Fixed some bugs concerning "Lock zoom scale".

Version 1.6.2, 03/17/2018
	Added to "File": Save JPEG file as EJPG file, Save EJPG file as JPEG file.

Version 1.6.1, 03/04/2018
	Adjusted image display logic when "Lock zoom scale" is checked.

Version 1.6.0, 02/14/2018
	Added settings: Always on top.
	Added settings: Mouse wheel, to switch images, or to zoom images.
	Replaced "Lock display region" with "Lock zoom scale".
	Added "Set photo as desktop background" to "File".

Version 1.5.0, 02/03/2018
	Added menu items to "View": 200%, 400%, 800%, 1600%.
	Window title: added image size and zoom scale.
	Fixed a bug of gif frame delay.
	Fixed a bug of max memory when the expected max memory exceeds 2GB.

Version 1.4.0, 01/20/2018
	Added Slideshow.

Version 1.3.1, 11/11/2017
	Made the + and - keys on the number key pad zoom in and out like the + and - keys located across the top of the keyboard do.

Version 1.3.0, 10/04/2017
	Fixed a bug of setting Maximal memory.
	Changed program icon color from black to blue.

Version 1.2.0, 05/13/2017
	Fixed a bug of GIF color:  GIF files with transparent color index larger than color map entry number are displayed with wrong colors.

Version 1.1.0, 04/23/2017
	Fixed a bug in GIF playing.

Version 1.0.1, 04/08/2017
	Fixed bug of TIFF encoding.

Version 1.0.0, 03/04/2017
	Initial version.