Solution:

When shooting still images, the colors of the [AF Frame] change as follows. (This is also the same when using the Touch Shutter function to shoot with the PowerShot ELPH 530 HS, 320 HS / IXUS 510 HS, 240 HS.)

[AF Frame]	What the color represents
(Green)	When the <shutter button> is pressed halfway and the subject is in focus, the color of the [AF Frame] changes to green.
(Yellow)	When the <shutter button> is pressed halfway and the subject is not in focus, the color of the [AF Frame] changes to yellow. In this case, the () icon appears on the lower right of the [AF Frame].
(Blue)	When the camera is tracking the subject while the <shutter button> is pressed halfway, the color of the [AF Frame] changes to blue. (Servo AF)*1 For the shooting modes in which [Servo AF] works, please refer to the following table.
*2 (Orange)	When pressing the <AF Frame Selector> button () to change the position and size of the [AF Frame]. <AF Frame Selector> is activated in the following condition: - When the [AF Frame] is set to [FlexiZone].
(Gray)	When the camera detects a person's face, but recognizes that it is not the main subject, up to two gray [AF Frames] are displayed. (Face AiAF) ([Face Detect] for PowerShot SX260 HS / PowerShot ELPH 530 HS, 520 HS / IXUS 510 HS, 500 HS) For the shooting modes in which [Face Detect] or [Face AiAF] works, please refer to the following table.

^*1 Servo AF is a function that tracks the subject and continually adjusts the focus and the exposure while the shutter button is pressed halfway.
^*2 PowerShot G1 X only.

Please see the table below to check if your camera supports each shooting mode.

Model	Shooting modes in which the function automatically works
	[Servo AF]*3			[Face AiAF] ([Face Detect] for PowerShot SX260 HS / PowerShot ELPH 530 HS, 520 HS / IXUS 510 HS, 500 HS*4
PowerShot G1 X
PowerShot SX260 HS PowerShot SX240 HS
PowerShot ELPH 530 HS / IXUS 510 HS PowerShot ELPH 520 HS / IXUS 500 HS PowerShot ELPH 110 HS / IXUS 125 HS PowerShot ELPH 320 HS / IXUS 240 HS
PowerShot A4000 IS PowerShot A3400 IS PowerShot A2400 IS PowerShot A2300 PowerShot A1300 PowerShot A810
PowerShot D20

^*3 If [Servo AF] is set to [On], the function works even if the shooting mode is other than listed above.
^*4 If [AF Frame] is set to [Face Detect] or [Face AiAF], the function works even if the shooting mode is other than listed above.