Filter to enhance the quality of image

Filter to enhance the quality of image - Printable Version

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Filter to enhance the quality of image - Stephen Liu - 05-24-2022

GIMP 2.10.18

The image (.png) attached here was scanned on Smartphone without scan software. Then I ran "mogrify" (IM command) converting it to positive image.

Code:

$ mogrify -negate image.jpeg

and then I cropped the image running Screenshot on "Image Viewer".

Please advise what filter shall I run to enhance the image quality and to remove its green color.

Thanks

Regards

RE: Filter to enhance the quality of image - PixLab - 05-24-2022

If those picture are B&W, to remove the green color, there are many ways, some which come to my mind.
Colors ➤ Hue-Chroma , put down the Chroma slider

[attachment=7963]

Also Colors ➤ Desaturate ➤ Desaturate /Mode Luma / HSV, your call
Colors ➤ Saturation /Scale at 0

Few ideas but not limited to Wink

RE: Filter to enhance the quality of image - denzjos - 05-24-2022

Colour picture? I did this (the result is poor like the original picture):
Colours / Levels (use pipets black / grey / white on the picture)
Then 'Colours / Hue-Chroma (use sliders)
[attachment=7964]

RE: Filter to enhance the quality of image - PixLab - 05-24-2022

(05-24-2022, 08:08 AM)denzjos Wrote: Colour picture? I did this (the result is poor like the original picture):
Colours / Levels (use pipets black / grey / white on the picture)
Then 'Colours / Hue-Chroma (use sliders)

Oh you're right those are colours

[attachment=7965]

RE: Filter to enhance the quality of image - rich2005 - 05-24-2022

That is a good result from denzjos using Hue-Chroma. Unfortunately a GEGL filter and not easily scriptable for your many Images.

IM mogrify -negate is only good for monochrome negatives and you used it on a colour negative. There are IM scripts for conversion see: http://www.fmwconcepts.com/imagemagick/negative2positive/index.php

However this is a Gimp forum and a Gimp process for a colour negative to positive is Colors-> Auto -> White Balance then Colors -> Invert.

How you might get a color-curves file out of your example file (are they all that small ? ) https://youtu.be/uODYcCwryFU duration 4 minutes

..and for a linux BIMP plugin see: https://www.gimp-forum.net/Thread-BIMP-version-2-6

RE: Filter to enhance the quality of image - Stephen Liu - 05-24-2022

Hi all,

Thanks for your advice.

Tried again. Re-scan the color film negative on Smartphone with Macro Mode

Start GIMP and convert the image to positive and crop it.

The image seems more clear. But still I couldn't adjust it to remove the green color

Pls refer to attached photos
photo-1 before adjusting Hue-Chroma
photo-2 after adjusting Hue-Chroma

Edit-1
====
Select
Color -> Auto -> Equalize
It seems the image more clear. But how to remove the red color ?

Pls refer to Photo-3 (Thumbnail)

Edit-2
====
Again select
Color -> Color Balance

Result - pls refer to Photo-4 (Thumbnail)

Regards

RE: Filter to enhance the quality of image - Ofnuts - 05-24-2022

(05-24-2022, 09:53 AM)Stephen Li Wrote: Tried again. Re-scan the color film negative on Smartphone with Macro Mode

Quality and smartphone in the same sentence...

The sensor in smartphones is very small and noisy. The images look good because they are heavily post-processed and usually checked on the smartphone screen. But this sort of precludes any decent post-processing. In addition the processing is done using algorithms that try to identify the kind of scene and to select a specific process, but I doubt they have anything specific to scanning negatives...

RE: Filter to enhance the quality of image - Krikor - 05-24-2022

Perhaps using Sallyanne's idea with `G'MIC - Repair - Unpurple' might be another option.
[attachment=7974]

RE: Filter to enhance the quality of image - Stephen Liu - 05-25-2022

(05-24-2022, 04:32 PM)Ofnuts Wrote:
(05-24-2022, 09:53 AM)Stephen Li Wrote: Tried again. Re-scan the color film negative on Smartphone with Macro Mode

Quality and smartphone in the same sentence...

The sensor in smartphones is very small and noisy. The images look good because they are heavily post-processed and usually checked on the smartphone screen. But this sort of precludes any decent post-processing. In addition the processing is done using algorithms that try to identify the kind of scene and to select a specific process, but I doubt they have anything specific to scanning negatives...

Thanks for your advice.

You're correct. Scanning on smartphone without scan software needs heavy post-editing but with scan software much better, less post-editing work.

I have tested "Filmbox" and "Photo Negative Scan". The quality of the positive images is much better. I'm now testing Google "Photoscan". I'll pay for either of them after finishing tests.

My another headache is finding a correct annotation of ImageMigick running their commands. I have read;

Annotated List of Command-line Options
https://imagemagick.org/script/command-line-options.php

But it is not easy.

Examples.
On GIMP
-> Colors - Auto -> Equalize

-> Colors -> Color Balance

What command of IM shall I use? What are their annotation? I spent sometime reading their Annotated List

Please shed me some light. Thanks

Also I have spent sometime collecting information going DSLR route and making heavy postings on other forums. I have no objection to buy a new DSLR camera but I expect the camera can be used for shooting daily life photos without purchasing additional LENS. Unfortunately up to now I haven't received an advice catering my need.

Edit
===
Example :
Smartphone scanning running Filmbox scan software, without cropping nor other post-editing, only running IM mogrify command, converting negative image to positive. (pls refer to photo attached)

Regards

(05-24-2022, 04:38 PM)Krikor Wrote: Perhaps using Sallyanne's idea with `G'MIC - Repair - Unpurple' might be another option.

Hi,

Thanks for your advice.

Whether you refer to;
GREYC's Magic for Image Computing
https://gmic.eu/gmic300/

What I expect to do is batch editing, running command lines. I have about a thousand film negatives to process.

I'm now investing which route shall I go ?

DSLR route
Smartphone route
Flatbed scanner route

I don't expect to go the last route. The scanning speed is very slow on Flatbed scanner. I have been scanning Photos/Doc/Negatives for >10 yrs on flatbed scanner. But still post-editing can't be avoided

Regards

RE: Filter to enhance the quality of image - Stephen Liu - 05-25-2022

Hi all,

Tried again scanning film-negatives on smartphone running "Photo Negative Scanner" (software)
Smartphone - Samsung Galaxy S9+ (> 8 years)
Macro Mode - 1.5

Following functions are provided on "Photo Negative Scanner"
1. Crop
2. Convert negative image to positive image

The quality of the positive images, without post-editing, is not bad. Please refer to attached photos.

Please advise which GIMP filter to be used to remove the green color?

If finally I decide going this route to digitize old color film negatives, I'll pay to remove the water-mark.

But I couldn't use Google Photoscan. I can take the shot but can't find where the image files are stored. They are not in Gallery folder. It is funny to me.

Regards