Apple Aperture 3 highlight alert,

[HeinrichR]

In aperture when I turn highlight alert on, Highlight alert will show areas in the photo where it is completely blown out/white, or shadow areas(black),
In the attachment is the exact same shot one with highlight alert on and one with highlight alert off, but in the highlight alert off image a lot of the red area is not blown out/white/no detail, Why ??
shouldnt only the blown out white area of the sun be turned red, or am I missing something?

[SteveG]

The highlight alert is probably set to a threshold level of something like 252 or 253.

For example if part of your image goes above this level then the alert is shown, even though it techinically is not blown out.

Don't know aperture, so can't advise if the threshold can be adjusted or not.

[elsahoffmann]

Preferences
: Advanced

what is your hot area set to?

[HeinrichR]

thanks Steve/Elsa, it is set at 100% Elsa, if I set it any lower it gets even worse and the red eventually covering most of the screen as the percentage value drops.