Hi everyone,
I’m not sure this is the best place for this, but being new here I’m not going to start a new thread. I’ve read all the posts but not the Python code and I’m painfully aware that there’s a lot of information that I’m only tangentially aware of (for example, I only discovered the reflectance-upsampling-methods branch today! So that is the “base” people are talking about…)
I’ve been trying to document a Spektrafilm GUI processing workflow, initially for my personal use as a starting point; this is my first draft:
Goal
Use Spektrafilm as an effect “finisher” for a developed RAW image. The Spektrafilm-processed image could be used as the final image or as a film-simulation reference.
This info is current as of 9 Jul 2026 and is specific to Spektrafilm on the reflectance-upsampling-methods branch.
In the RAW Developer
Get white balance, levels, contrast, shadows & highlights and saturation “in the ballpark”.
Do your cropping, straightening, noise reduction here. Perform dodging and burning on specific parts of the image here.
If you need to do relatively specific colour grading on specific hues or colours, do it here.
Export the RAW image as a 16 or 32-bit linear REC.2020 TIFF (in Lightroom, the easiest way to do this is to export with “HDR Output” selected with 32 bit “HDR Rec 2020”).
Spektrafilm Colour Spaces
Load your TIFF image in Spektrafilm.
MAIN → INPUT
Set input colour space accordingly (ITU-R BT.2020 for REC.2020)
MAIN → OUTPUT
Set output colour space to taste (ProPhoto RGB is a good starting point)
Film & Print Profiles
MAIN → PROFILES
Select an appropriate film profile and print profile.
FILM → COUPLERS
If you want to REDUCE the intensity of the “effect”, set “amount” to a value < 1
Levels, brightness & darkness
MAIN → ENLARGER
Modify “print exposure”. Don’t be afraid to increase brightness to bring up some shadow detail (use a number < 1) at the cost of some highlights. You can compensate for this later.
PRINT → PREFLASH
Tame the hot highlights here. Start at 0.01, increase by 0.01 as appropriate. I try to always enable preflash, because it gives you additional colour grading capability (see later).
MAIN → CAMERA
If you need more serious highlight/brightness exposure compensation, try tweaking “exposure compensation ev”. I have only found this useful if radical highlight control is required, but this should really have been handled in the RAW developer prior to TIFF export.
PRINT → CHEMISTRY
Tweak the gamma/strength of highlights and shadows by changing “gamma factor fast” and “gamma factor slow” accordingly. I find changing the “gamma factor” to be too inexact.
PRINT → BASE
Adjust print (image) density by tweaking “scale” if necessary.
Colour balancing
MAIN → ENLARGER
Adjust “print y filter shift” and “print m filter shift” to get the colour balance in the rough ballpark.
PRINT → CHEMISTRY
You can then tweak red, green & blue channels by adjusting “gamma factor red”, “gamma factor green” and “gamma factor blue”.
PRINT → BASE
You can strengthen or weaken global cyan, magenta and yellow on the print by adjusting “cyan”, “magenta” and “yellow”
PRINT → PREFLASH
If preflash is enabled, you can tweak the colour of the preflash. Think of this as tweaking the colour balance of the highlights, by adjusting “y filter shift” and “m filter shift”
Diffusion
Note: The Spektrafilm GUI preview doesn’t seem to be able to show the effect of diffusion
PRINT → DIFFUSION
Enable this by ticking ‘active’, then select filter family and strength.
Grain
FILM → GRAIN
Adjust “rms granularity” to taste. For values that replicate decent medium format scans for 45-100 megapixel images, start at about 25-40.
Halation
More so than other programs and plugins, this appears to be quite film-stock and scene-specific and is potentially very subtle.
Start by adjusting the halation effect multiplier via FILM->HALATION “halation amount”.
You may have to use very large values to see a difference in some situations, depending on the scene and base image size. For my large 45-100 megapixel images, multipliers of 50 or 100 might be required to see significant changes at a pixel level.
Film Export
Scan the image by clicking the “Scan” button. After this is finally complete, save the processed image by clicking on “Save”. Save the file as a TIFF/TIF.
Questions
Given that I’m relatively new to Spektrafilm, have I made any obvious errors?
For example, is there actually a better way to tweak halation?
Are there other effective to adjust the image that I haven’t used? For example, I have almost completely ignored Couplers because, well, too much magic.
Uploaded JSON settings are a useful starting point but are often lacking context. Let’s try and build out some best-practices!
