Re: Determine the amount of white/brightness in an image

Subject: Re: Determine the amount of white/brightness in an image

From: Troy Koelling <email@hidden>

Date: Wed, 22 Jul 2009 15:24:47 -0700

Delivered-to: email@hidden

You might try the ImageHistogram plugin example.

Remember that reading pixel values out of an image usually requires downloading off the GPU, which is very expensive. If at all possible, it would be good to process the image first to make it smaller, or perhaps use one of the Core Image patches to find aggregate information for an image.

On Jul 22, 2009, at 3:09 AM, David Langford wrote:

G'day all

I have a id<QCPlugInInputImageSource> and I want to determine how much white or brightness is in the image.

I was thinking of changing it to a texture representation and using glReadPixels. Then looping over the retrieved pixels and individually seeing which ones are white.

But I have an hunch there is a better/easier way to do this, but googling isn't helping much.

Has anyone ever tried this?

Does anyone have any ideas?

Should I just continue with how I was going to do it?

Cheers

Lango

_______________________________________________
Do not post admin requests to the list. They will be ignored.
Quartzcomposer-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quartzcomposer-dev/email@hidden

This email sent to email@hidden

_______________________________________________ Do not post admin requests to the list. They will be ignored. Quartzcomposer-dev mailing list (email@hidden) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/quartzcomposer-dev/email@hidden This email sent to email@hidden

References:
	>Determine the amount of white/brightness in an image (From: David Langford <email@hidden>)