Regarding aggregation at multiple levels

[Sriram Somanchi]

Thanks Kent for your response. 


I understand that it might not have to do with OpenSlide library, however I
want to understand how this aggregation is done. I tried this on the sample
file that I have downloaded (CMU-1.svs) from openslide webpage and I get the
following output. 

Like I said it might have to do with the library, however, it will be great
if I can directed to documentation about this aggregation over multiple
levels. 

 

Thanks,

Sriram

 

Output on CMU-1.svs file:

 

4x4 grid at level 0:

The level 0 width 46000, the height 32914

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

 

1x1 grid at level 1:

The level 1 width 11500, the height 8228

The alpha 255, red 238, green 239, blue 238

 

From: Kent Johnson [mailto:kent3737 at gmail.com] 
Sent: Wednesday, November 07, 2012 1:35 PM
To: Sriram Somanchi
Cc: openslide-users at lists.andrew.cmu.edu
Subject: Re: Regarding aggregation at multiple levels

 

My understanding is that OpenSlide is just giving you the data from the SVS
file. So the difference in red is caused by whatever program wrote the file,
not OpenSlide.

 

Kent

 

On Wed, Nov 7, 2012 at 1:09 PM, Sriram Somanchi <ssomanch at andrew.cmu.edu>
wrote:

Hi,

 

I am new to using virtual slides and openslide library to access these
files. I have a few Aperio (.svs) files that I could open with open slide. 

 

My question is how is the aggregation done at multiple levels. I see that
the aggregation RGB of 4x4 grid is not the 1x1 grid at the higher level (my
down sampling is ~4). I have attached a small snippet of the code for
reference. Can someone please explain how the aggregation is done across
multiple levels? 

Otherwise, can you please direct me to documentation which will help me
understand this aggregation

 

Thank you for your help.

 

Sriram

 

Code:

openslide_read_region(slide, buf, 0, 0, 0, 4, 4);

openslide_read_region(slide, buf1, 0, 0, 1, 1, 1);

 

Output:

 

4x4 grid at level 0:

The level 0 width 107046, the height 87978

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

The alpha 255, red 239, green 239, blue 239

 

1x1 grid at level 1:

The level 1 width 26761, the height 21994

The alpha 255, red 241, green 241, blue 239


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