A large difference in reflectance values ​​on the same pixel - Prisma after co-registration in QGIS??

[tazrart]

Dear users Co-registration plugin in QGIS,

I wanted to study the spectral signature of a lake. Indeed, I correctly imported the Prisma L2D product under enmap-box v 3.10 (he5 to tif format conversion). The values ​​vary between 0 and 1.

However, Prisma images are always shift with reality (compared to google earth image).

Gooogle earth image :

Prisma image :

So I applied the correction via the QGIS Co-registration plugin (Automated global co-registration) and I have a good result (good correction) :
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Prisma image after correction :

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However, the values ​​of the pixels before and after correction are not identical. Indeed, the values of the corrected image have multiplied by a factor of 10⁴ compared to the initial image but that is not the problem.

The real problem that the values ​​of the same pixels have been changed too much. See below, I folllow the same pixel (blue outline pixel) and the reflectance (first band) vary from 1155 to 7509 after the correction.

Values on one pixel after correction :

Values on same pixel before correction ;

I have tested all resampling methods of co-registration plugin (cubic, bilinear, nearest neighbour,…) and the results are almost the same and the values ​​are too far from the initial image ("Mode" method not function for me , I don't know why!)

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In my opinion, I cannot work with the reflectances of the corrected image. They are too far from reality.
Have you noticed this difference? Is there a method to apply without changing the initial values?

Thank you,

[danschef]

See my comment to the same issue here.