Enhancing faded receipts

[toronto070]

Hi, 

I'm a new GIMP user, and installed it as a recommended "auto fix" for photos, so not necessarily going to be the best at leveraging manual adjustment features.  I've seen videos where a paid software is used to adjust the levels with great success in enhancing faded receipts.  I've played around with this a little bit in GIMP, but have no idea what I'm doing - any help or advice? 

Thanks!

[Ofnuts]

Normally the Color>Brightness/Contrast tool is enough. Increase contrast and perhaps compensate a bit by lowering the brightness.

However, if these come from a scanner, then the Brightness/Contrast control of the scanner software can often do a better job (because it has more data to work with). And if these receipts are shot with a smartphone, the better the shot (good an uniform lighting), the easier it is to work on (otherwise increasing contrast will also increase the defects) but the smartphone camera app may have some brightness/contrast control itself.

For more details, we need a sample receipt (or anonymized extract thereof).

[toronto070]

(11-01-2017, 09:08 PM)Ofnuts Wrote: Normally the Color>Brightness/Contrast tool is enough. Increase contrast and perhaps compensate a bit by lowering the brightness.

However, if these come from a scanner, then the Brightness/Contrast control of the scanner software can often do a better job (because it has more data to work with). And if these receipts are shot with a smartphone, the better the shot (good an uniform lighting), the easier it is to work on (otherwise increasing contrast will also increase the defects) but the smartphone camera app may have some brightness/contrast control itself.

For more details, we need a sample receipt (or anonymized extract thereof).

Thanks for your response.  I have several faded receipts (none of which is really confidential...there's just a bunch of them with varying levels of faded print, so hard to provide a one size fits all example), and I've tried the contrast / brightness scanner settings - contrast seems to work best, but the faint print on the receipts still doesn't always get picked up. I'll try taking a picture with my phone as you've suggested - it has a pretty good camera. Thanks again.

[gramp]

Might try illuminating under UV or IR. Ink might accidentally show up better.

Also might try decomposing into color channels and see if one of them accidentally has a better image than the others.

[Ofnuts]

(11-02-2017, 05:22 PM)toronto070 Wrote:

(11-01-2017, 09:08 PM)Ofnuts Wrote: Normally the Color>Brightness/Contrast tool is enough. Increase contrast and perhaps compensate a bit by lowering the brightness.

However, if these come from a scanner, then the Brightness/Contrast control of the scanner software can often do a better job (because it has more data to work with). And if these receipts are shot with a smartphone, the better the shot (good an uniform lighting), the easier it is to work on (otherwise increasing contrast will also increase the defects) but the smartphone camera app may have some brightness/contrast control itself.

For more details, we need a sample receipt (or anonymized extract thereof).

Thanks for your response.  I have several faded receipts (none of which is really confidential...there's just a bunch of them with varying levels of faded print, so hard to provide a one size fits all example), and I've tried the contrast / brightness scanner settings - contrast seems to work best, but the faint print on the receipts still doesn't always get picked up. I'll try taking a picture with my phone as you've suggested - it has a pretty good camera. Thanks again.

You can also try the Threshold tool, but a frequent result is that it threshold cracks, folds and spot in the paper at about the same time it thresholds faint print, so the result isn't always very readable.