Problem with Invert

[sockit]

I am a newcomer and was testing Invert with a colour negative but find that it is inverting only to a mono monochrome image with a single light blue colour. What am I doing wrong? I have tried to select that it is an RGB coour but evidently don't know what I am doing.

Thanks

[davescm · Accepted solution]

A colour negative has an orange mask which needs to be removed. When inverted this will look blue.  So invert then use curves to set the black, white and mid tone values for the image.

Dave

[sockit]

Thanks for your comment.   I realise that aspect of the colour. However
the image was otherwise black and white with no reds or greens anywhere
Thank. I had cut and pasted the image into Photoshop and subsequently
tried import the image.   I am still learning how to compensate for the
blue tinge though that seems to possibly be better. I appreciate your
rapid response as I am sill lost in this medium though have made
lightroom work reasonably well. I am seeking a way to do batch
inversions. as I have a lot of images to do this on.

[D Fosse · Accepted solution]

Getting a good result from color negatives is pretty difficult. You need to work on each channel separately.

The orange mask is not as easy to neutralize as one might think, because it's not a fixed, flat density. It varies with the other dye densities. Some pretty advanced science went into that mask. But from what I've read it improved the color gamut enormously.

The net implication is that you may have to do a lot of individual color adjustments after you get a decent overall result.

[sockit]

Thanks for your comment.   I have been using the method for Lightroom in which you reverse the slope of each colour so that it extends across the length of the display on the X axis. It works really well and I have been modifying the upper and lower end of each curve as needed to change the luminance of either the highlights or lowlights of each colour. I found that I could increasing the focal point of each image that way as well as removing the blue tinge. My only problem is that I have a huge number of negatives to process and that it takes a few minutes for each individual image. There is also the need to export and reimport the file. This fixes the colour curve and allows the other controls to be used in the normal way. I just don't have enought time to take the months of daily work needed. However the results are beautiful.

[Per Berntsen]

The Color Negative preset in the Curves panel will remove the blue cast in the inverted image, and will in many cases produce good results, but you may need to adjust the individual channels.

Start out by creating a Curves adjustment layer (Layer  > New adjustment layer > Curves), then choose the Color negative preset.

[Conrad C]

Lots of good advice already. The tricky thing about color negatives is that the amber mask and the dye layers are not the same across different brands and types of negative film, so there is not one solution that works every time in Photoshop. If you do it manually, you usually have to tweak the curves in just the right way.

If you are going to do this a lot, for example if you need to process a large number of digitized color negatives reliably at high quality, you can look into a specialized solution such as:

• VueScan or similar scanning software that has a good color negative inversion feature. VueScan comes with profiles for different types of color negative film, and also has options that help compensate for faded color dyes due to age. It can save in formats Photoshop can open. I use this software.
• Negative Lab Pro, which provides very high quality inversions, and can also emulate the color models used by classic film processing machines such as Noritsu and Frontier. But Negative Lab Pro is a plug-in for Lightroom Classic, not Photoshop.

You might want to watch the video on the Negative Lab Pro home page. It’s a good short summary of what’s involved in digitally inverting and processing color negatives, and why it can be a challenge.

[sockit]

It seems that Negative Lab Pro is very useful and what I need. However
does it remove the issue that one encounters with the manual approach
where the controls in Lightroom are all reversed? The need to export and
then reimport the image creates a lot of complexity in the work flow. 
My other question is whether it is necessary to use RAW image files?
Currently I am using jpeg though could switch to Raw. Does it enhance
the result to do that ?

Thanks

Sockit

[Per Berntsen]

Some scanning software will let you save as "raw" or DNG, but this is not true raw files (like raw files from a digital camera), and in my opinion these formats don't offer any advantages.

A 16-bit Tiff that contains all the information in the negative, with no shadow or highlight clipping, is as good as any raw file.

Jpg should be avoided – it uses destructive compression, and is not suited for editing.

Every time you save a jpg, it is recompressed, and image quality will suffer.

[Conrad C]

I am not (yet) a Negative Lab Pro user, so the following might not be completely correct. From what I understand, first you make initial corrections in Lightroom Classic in the Negative Lab Pro plug-in, to set up a good conversion. Then, if you want to edit the image further using Lightroom Classic controls, you use NLP to convert the selected negative scans to TIFF. That step both applies the NLP corrections and converts to positive, so any edits to the converted TIFF positive image using Lightroom Classic tools will be normal, not reversed.

But now you have two files to manage for the image: The inverted original scan, and the NLP-processed positive TIFF file. I guess if the TIFF positives are good enough you can lose the scans, but again, I’m still learning about Negative Lab Pro myself.

If you’re coming up with more questions about Negative Lab Pro, there is a forum on their web site where you’ll get better answers from people who actually use it.

In these workflows, people commonly use DNG or TIFF for quality reasons: The digitized file is the starting point for major corrections, so you want a format that keeps as much quality as possible from the negative. JPEG is used only as a format for exporting images that need to be compressed for uploading and won’t be edited any further.

[sockit]

Hi Conrad and Stephen and Per

Thanks for all of your help.  This has given me a huge boost in coming to grips with Photoshop and extensions to Lightroom.  I will explore all of these opportunities.

Terence

[Stephen_A_Marsh]

A good starting point has often been to sample the orange mask colour, fill a new layer with this colour, invert the colour and blend in color mode at 50% opacity. This method often helps with setting up batch automation to at least get the images at a workable starting point, before inverting, setting neutral endpoints and curving each channel to bring out the colour working by the numbers to known memory colours.