un probleme avec / problem with "-levels 1 213"

[payaxnv]

bonjour (Englih(?) is at the end)
je cherche a récupérer de vieux scans qui sont un peu gris et de faible résolution.
Dans xnview ca marche plutot bien avec:

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nconvert -levels 0 213 -ratio -rtype lanczos -resize shortest 1920  

mais qund j'inclus cette commande dans un BAT (avec nconvert donc) j'ai des images qui sont éclaircies (grillées, beaucoup plus que lors du traitement manuel) sur environ le 1/4 supérieur, le reste étant inchangé.
J'ai essayé de séparer l'aclircissement du redimensionnement, de changer de format JPG> eclaircissement et BMP > JPG
rien n'y fait . EX (elles sont toutes comme ca !)

img_1920_RSD_003.jpg

il y a t il un moyen de contourner cela ?
d'autant plus frustrant que ca marche mannuellement

Hello;
trying to clean old scans, without real white and black
in xnconvert treatment and conversion work well
"export to nconvert" is:

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nconvert -levels 0 213 -ratio -rtype lanczos -resize shortest 1920  

when this line is used in a BAT file it makes the upper quarter of each image many more clear than specified, the 3/4 untouched

i have try to put

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-levels 0 213

at different pales, i try to convert in different formats, to make the conversion before resizing... NO WAY
Any way to make it work ? (It is fine doing it thru XNCONVERT )
Thanks

[cday]

quand j'inclus cette commande dans un BAT (avec nconvert donc) j'ai des images qui sont éclaircies (grillées, beaucoup plus que lors du traitement manuel) sur environ le 1/4 supérieur, le reste étant inchangé.

To be clear:

In XnConvert all images are converted correctly?

But in NConvert [tested in a batch file] all images, or only some images, are not converted correctly?

Could you upload an example file that doesn't convert correctly using NConvert, so that Pierre can possibly test it?

Edit:

The XnConvert Resize dialog has a setting for Enlarge/Reduce which I don't see in your code, or as an option in the NConvert help file, possibly not supported in NConvert??

I see there is the following option associated with the resize option, I don't know if it could be relevant, probably not??

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-resize fill w h    : Scale by filling the box wxh

Pierre?

[payaxnv]

thanks for your answer:
In XnConvert all images are converted correctly?
YES

But in NConvert [tested in a batch file] all images, or only some images, are not converted correctly?
NO... NONE

Could you upload an example file that doesn't convert correctly using NConvert, so that Pierre can possibly test it?
yes (ALL the images are mistreated (tested on #50 different one))

I have try before or within resizing: same wrong result

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 %nconvert_path%  -overwrite -out bmp -levels 1 213 -o img_1920_RSD_### *.jpg
 %nconvert_path%  -overwrite -out bmp  -dpi 72 -resize 1920 0 -ratio -rtype lanczos -subsampling 2 -o img_1920_RSD_### img_1920_RSD_*.bmp

or

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%nconvert_path% -levels 0 213 -ratio -rtype lanczos -resize shortest 1920 -out bmp -o img_1920_RSD_### *.jpg

original image (exemple)

[XnTriq]

Could you please try the icc_ie (Ignore embedded ICC profile) option, payaxnv?

[payaxnv]

no result (same result) with:

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%nconvert_path% -icc_ie -levels 0 213 -ratio -rtype lanczos -resize shortest 1920 -out bmp -o img_1920_RSD_### *.jpg

I have tested in 2 steps: 1: just change levels then 2 resize...same bug
so it is in the "level" command
i try also level 1 123 instead of level 0 123 > same thing

All images have the same problem:

[payaxnv]

PS
tested with another bunch of images from another sources > same result

[cday]

PS
tested with another bunch of images from another sources > same result

I think testing with a single image that shows the problem (the JPEG you posted above?) and the minimum code that produces the problem (seems to be the levels operation?) is the best way to proceed...

[I'm afraid I don't have any time today, or othe ideas immediately... ]

[payaxnv]

some info:
tested with a total of #200 images from various sources > same result
i forgot to mention that during the bat, nconvert says "ok" to each operation

most interesting: tested with -autolevels :

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 rem 2 operations 
 rem intermediate images are kept for debugging
 rem 1 works on levels
 %nconvert_path%  -icc_ie -overwrite -out bmp  -autolevels -o img_1920_RSD0_### *.jpg
rem 2 resize
 %nconvert_path%  -overwrite -out bmp -q 90  -dpi 72 -resize 1920 0 -ratio -rtype lanczos -subsampling 2 -o img_1920_RSD_### img_1920_RSD0_*.bmp
 

NOT the same errors
BUT mistreatment appears in large (double page) images

> seems to be insufficient buffer to work
if you agree, please contact the author of this wonderful tool

if i make a mistake, please correct me
thanks for helping

EDIT:
im not sure as before, next tests show errors also with -autolevels, about 2% of images:ex:

[payaxnv]

another example:

[cday]

I think you need to try to isolate the problem to one or two example files, and the simplest code required to reproduce the issue, so that it can be reproduced easily and investigated...

[payaxnv]

the code is in the post above :
in fact only the first command is interesting, second one resize (properly) an already altered image

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 rem 2 operations
 rem intermediate images are kept for debugging
 rem 1 works on levels
 %nconvert_path%  -icc_ie -overwrite -out bmp  -autolevels -o img_1920_RSD0_### *.jpg
rem 2 resize
 %nconvert_path%  -overwrite -out bmp -q 90  -dpi 72 -resize 1920 0 -ratio -rtype lanczos -subsampling 2 -o img_1920_RSD_### img_1920_RSD0_*.bmp

the test images are in the 2 post before

you can change

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-autolevels

with

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 -levels 1 123

or

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-levels 0 123

to reproduce this problem

[xnview]

it's not really a bug, -autolevels work on all separate component, -autocontrast works closest as -levels

With your pictures, -autolevels doesn't work correctly

[payaxnv]

OK i understand,
but it s not working fixed levels (should be apply to all images) as -levels 1 123
?