Re: patch-fu

Julia:
Is the "double conv[65536]" related stuff really needed for the  
performance improvements?

David:
The feature-extractor is obviously capable (at least before these  
patches) of dealing with images of sizes other than 256 by 256.
If I were to alter gift-add-collection.pl to resize the images to  
something other than 256x256, how would that affect the results of a  
query to the giftserver?

/Jonas



17 aug 2006 kl. 11:13 skrev David Squire:

> Jonas Lindqvist wrote:
>> Hi!
>>
>> I feel an urge to ask some questions... (Perhaps silly, but  
>> anyway... I know I could probably find the answers by digging in  
>> the code a bit deeper, but I admit I'm lazy...)
>>
>> * The function gabor_filter, in gabor.c, now uses a fixed array of  
>> 65536 doubles, instead of callocing the size indicated by the  
>> width and height that are passed as parameters to gabor_filter 
>> (...). Very well...
>> Are the width and height always 256, or can they be 128*512 or  
>> 2*32768 or whatever?
>
> That is not a change I would approve. The width and height are  
> presently
> always 256x256, but this was always intended to be a temporary  
> measure.
> Code that does not need this assumption should not make it. The code
> should be kept as open for extension and generalization as possible.
>
>>
>> * I guess that most modern CPUs have some kind of SSE2-ish  
>> features that gcc could use, but what would the effect of the  
>> patch be for an architecture that lacks it? (Something seriously  
>> old, pre MMX, or something else that perhaps one would not use for  
>> this application anyway...)
>>
>> * Wouldn't memset be faster than looping and setting to zero?:
>>     for (i = 0; i < width*height; i++)
>>       {
>>         conv[i]= 0;   /* needs to be zeroed */
>>     }
>
> calloc should handle this.
>
>> and isn't width*height always 65536?
>>
>
> See my comment above.
>
> I've just got back from a few weeks away from the internet. Much  
> catching up to do...
>
> Regards,
>
> David
>
>
>
> -- 
> Dr David McG. Squire, Senior Lecturer, on sabbatical in 2006
> Caulfield School of Information Technology, Monash University,  
> Australia
> CRICOS Provider No. 00008C        http://www.csse.monash.edu.au/ 
> ~davids/
>
>
>
>
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