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IIQ 16 bit - stretched histogram

Posted: Thu Jun 20, 2024 6:44 pm
by Elena Donovan
Hi David,

I wonder if you have some comments, I noticed the histogram is automatically stretched when working with 16 bit imagery, is there a way to update? or can we default to 8bit?

Re: IIQ 16 bit - stretched histogram

Posted: Thu Jun 20, 2024 6:45 pm
by David Alamillo
Hi Elena,

Sure, I would be happy to help.

IIQ files are 16 bits by default, leading Correlator3D to stretch the histogram when displaying them. On disk, the colors remain the same, it's simply a different way to display it and optimize the histogram (which usually exaggerates defects).

Suggestions:
- Export a mosaic in .tiff format, important to note, when comparing colors use the same software to validate them.
- Generate the orthos in 8 bits using the corresponding option in our orthorectification dialog. This would avoid dealing with the stretched histogram effect, if not interested in a 16-bit product.
- Enter the mosaic editing tool, and un-toggle the "stretch" option. The button is located top-right in the main toolbar.

Keep me posted if this helped.

Re: IIQ 16 bit - stretched histogram

Posted: Tue Jun 25, 2024 1:58 pm
by Elena Donovan
Thanks a lot! this is exactly what I needed.

Cheers,

Elena

Re: IIQ 16 bit - stretched histogram

Posted: Mon Mar 17, 2025 12:25 pm
by Justin Lewis
Hi guys,

I was looking for answer on why my 16 bit imagery seemed a bit "odd" in Correlator vs opening in QGIS for example, this topic explains this perfectly, and will always double check my results in QGIS when exporting a 16 bit mosaic.

Re: IIQ 16 bit - stretched histogram

Posted: Tue Mar 25, 2025 4:44 pm
by Justin Lewis
I have another question, It would be possible to add a new ortho and mosaic folder in the layer tree and have both outputs (8bit and 16bit) in the same project, correct?

Re: IIQ 16 bit - stretched histogram

Posted: Wed Mar 26, 2025 11:37 am
by David Alamillo
Hi Justin,

Absolutely, simply add a new folder by clicking the + sign when hovering over the orthos or mosaic section in the layer tree.