Regarding aggregation at multiple levels

[Sriram Somanchi]

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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