Acv curves of native ones for Affinity

[Richsul]

Folks,

There are thousands of photographers making platinum prints, palladium, gum, oil prints, resinotype, cyanotype, etc. 

Originally these were historic processes and were made via contact negative. Today, we use a digital negative made in a digital printer. Each process, needs a negative, and the negative needs to be corrected for the process's formula, paper, climate conditions (Key West vs Santa Fe,) and printer and inkset, (Matte Black vs Photo Black,) or RGB, vs grayscale.) Making a curve is tedious and we share them, At Bostick & Sullivan, at Photrio, Alternative Photography, and so on. Many are switching over to Affinity, my favorite too... but... we have to keep a subscription to Photoshop to be able to apply to make a negative on Pictorio. This is nice for Adobe, but not to Affinity's users.

We need to be able to read a ACV correction curve and apply it to a digital image before printing. This is because most of these processes are printed using the blue and near UV spectrum and various inks transmit UV light in a non linear fashion. For instance a tiny amount of yellow increases contrast.

We are in need of Affinity:

Being able to read and apply a ACV curve from Adobe,

Or convert and existing ACV curve to an Affinity curve.

Or at least be able to create a curve in Affinity.

This is done by printing a step wedge and scanning the print and coming up with a correcting value and building a new curve from the corrected values.

A sample curve created this weekend is attached.

Thanks.

-- Dick Sullivan HonFRPS
Honorary Fellow of the Royal Photographic Society
www.bostick-sullivan.com
Santa Fe, New Mexico

 

 

10%pt_AFOplatinumprintcurve.acv

[walt.farrell]

Is there a particular reason you posted this under Feedback for Affinity Designer, rather than Photo?

If not, an administrator might want to move this topic.

[Richsul]

Yes, please move to Affinity Photo, it was my fumbling around finding where the features forum was located. The right church, wrong pew!

 

Thanks

[fde101]

From what I can see, an ACV file is a preset for curve adjustments.  In that case, anything that can be done with an ACV should also be possible with a LUT, which can be applied in Affinity apps using a LUT adjustment layer.

If you can use a Curves adjustment within the Affinity apps to do what you need, you can export it as a LUT then someone else can apply it using the LUT adjustment layer.

Not sure if there is a convenient way to convert an ACV to a LUT?

[Richsul]

Thanks, I'll look into the LUT. What is important would be to port over existing ACV curves. 

Where to find information on LUT? I am on the prowl.

 

--Dick Sullivan

[fde101]

1 hour ago, Richsul said:

Where to find information on LUT?

In general?  All over the internet - example: https://www.shutterstock.com/blog/how-use-luts-color-grading

 

For using them in Affinity Photo:

https://affinity.help/photo/en-US.lproj/pages/Adjustments/export_3dLut.html

https://affinity.help/photo/en-US.lproj/pages/Adjustments/adjustment_3dLut.html

[Largo Lagrande]

If you guys still own Photoshop, you can use it to convert the .acv file to a .cube LUT file. And then import the LUT file in Affinity Photo !

Here are the steps required to convert an .acv file to a .cube LUT file in Photoshop :

1. Import the .acv File into Photoshop:

   • Open Photoshop.
   • Open a new image or create a blank file.
   • Apply the .acv file using the Curves Adjustment Layer.
     • Click on Layers > New Adjustment Layer > Curves and load the .acv file using the load option within the curves adjustment.

2. Export the LUT:

   • With the curves applied to the image, go to File > Export > Color Lookup Tables.
   • Choose the file format as .cube.
   • Save the LUT file.
   • For a detailed description about how the export dialog options work, please read https://helpx.adobe.com/photoshop/using/export-color-lookup-tables.html

Now to apply the .cube LUT file to an image in Affinity Photo, follow these steps :

1. Open Your Image in Affinity Photo:

   • Launch Affinity Photo and open the image you want to work on by navigating to File > Open, and selecting your image file.

2. Add an Adjustment Layer for the LUT:

   • In the Layers panel (usually located on the right side of the workspace), click the Adjustments icon (a circle split into black and white halves).
   • From the dropdown list, choose LUT. This will add a LUT adjustment layer on top of your image.

3. Import the .cube LUT File:

   • Once you’ve selected the LUT adjustment, a new window will appear for the LUT settings.
   • Click the Load LUT button, which allows you to browse and select a .cube file from your computer.
   • Navigate to the folder where your .cube LUT file is located and select it.

4. Apply the LUT to Your Image:

   • After loading the .cube file, the LUT will be applied to your image immediately.

That’s it! Your LUT is now applied to your image, and once inverted, bam! you have your digital negative ready to be printed !