JPEG QUALITY to Q=95 AND RES_CORRECTION

[titionex]

JPEG QUALITY to Q=95 AND RES_CORRECTION
This PR introduces two important fixes to the image conversion process in Converter.py:

JPEG Quality Enhancement: Forced JPEG compression quality to Q=95. The default behavior of 'tiffsave' uses Q=75, which can lead to excessive compression artifacts. Increasing this value ensures better image fidelity for large-scale processing.

Resolution Correction (MPP): Fixed a bug where the original MPP (Microns Per Pixel) was being incorrectly reduced by a factor of 10 (e.g., scaling
0.25
down to
0.025
). This fix ensures that the spatial metadata remains accurate and consistent with the original slide resolution.

[guillaumejaume]

Thanks for the PR.

On the MPP point, the current implementation is correct when mpp is in microns per pixel and TIFF resolution is stored with resunit=CM.

xres = 1.0 / (mpp * 1e-4)
yres = 1.0 / (mpp * 1e-4)

Why:

• 1 µm = 1e-4 cm
• mpp * 1e-4 gives cm/pixel
• TIFF xres / yres expect pixels per cm

So the correct conversion is:

pixels/cm = 1 / (mpp * 1e-4)

For example, if mpp = 0.25, then xres = 40000, which is correct.

Using 1e-3 would convert to mm, not cm, so that would be wrong with resunit=CM.

The JPEG quality change is a separate discussion, but the proposed MPP “fix” is not correct as written.