[GEM-dev] Re: GEM: pix_image reloading image already loaded

[Etienne Desautels]

On 04-10-28, at 20:41, chris clepper wrote:

> On Oct 28, 2004, at 2:00 PM, Etienne Desautels wrote:
>
>>
>> Hi Chris,
>>
>> Thanks for your answer.
>>
>> I just replace my pix_image object with pix_film and it works. I also 
>> send it a RGB colorspace message at loading time, this way PNGs are 
>> showing fine. Without the RGB message, JPGs are showing fine but not 
>> PNGs. Do you have any ideas why it works with JPGs and not PNGs?
>
> Quicktime will convert YUV to RGB automagically, but not the other way 
> around.  pix_film defaults to YUV because it is the proper color-space 
> for video and also quite a bit faster than RGB.  PNG images are RGB 
> with lossless compression, while JPEG are YUV with lossy compression 
> applied.

Oh! I didn't know that JPEG was in YUV. I was thinking that most image 
format were in RGB. That probably also explain why JPEG are loaded 
faster then PNG? Thanks for the explanation.

I just think about a question that I have for quite some time. I'm 
using pix_video with a firewire webcam to do some motion 
tracking/presence detection. I would like to adjust the settings of the 
webcam (color balance, brightness, etc.) but when I send a dialog 
message to pix_video, the normal QT dialog open and then pd freeze. I 
have to hit ^-C to quit pd. Do you have any ideas on this ?

Etienne