Is there a way to replicate this Photoshop tutorial in Photo?

[Frozen Death Knight]

Just saw this video where you use the Photoshop layer Divide to neutralise the colours of an image. Couldn't find any layer setting named Divide, so wanted to ask if Affinity has something similar to it?

 

[smadell]

Good Morning, FDK...

I saw the same video and was also dismayed to find out that AP does not have a Divide blend mode. I did a little reading, and it turns out that you can come pretty close to duplicating this by using Apply Image. I even tried to make all this into a macro (to make it less cumbersome) but could not manage it. Anyway, here's the process:

1) Create a new Pixel layer above the image with the Color Cast.

2) Sample an area on the original image that is supposed to be white (I used the part of her dress that was used in the video.)

3) Fill the empty pixel layer with that color.

4) With the solid color pixel layer selected, choose Apply Image...

5) Drag the original image layer into the Apply Image dialog so that it is that layer you're applying.

6) At the bottom of the Apply Image dialog, check the Equations box, and enter the following:

   DR = 1 / (DR/SR)

   DG = 1 / (DG/SG)

   DB = 1 / (DB/SB)

   DA = SA

7) Hit the Apply button.

It's a cumbersome process, but it seems to work.

[John Rostron]

43 minutes ago, smadell said:

  DR = 1 / (DR/SR)

Mathematically, this is equivalent to DR=SR/DR. Is that the case in practice?

John

[Frozen Death Knight]

@smadellThanks for the help! I tried it and it works okay on images with only one layer. However, with several layers it becomes way too cumbersome to apply to every area. I guess we just have to ask the devs to add it in, since it could be pretty handy to have from time to time. : )

[Murfee]

There is an easier way

• Sample the area that should be white
• Fill a new Pixel layer with the sampled colour
• Invert the filled Pixel Layer with the Ctrl/Cmd I keyboard shortcut
• Change the blend mode of the filled pixel layer to Colour Dodge

[smadell]

John... I always thought I was good at math, but I didn't catch that. Using DR=SR/DR and so forth certainly makes the typing easier. And the results are the same! Good catch.

FDK... If you have more than one layer, but all the layers above the image are adjustments, you could just put the pixel layer above the photo layer and do the Apply Image there. If you've got multiple layers with pixels on them, then doing a Merge Visible at the top of the stack would get you a summary photo to work on; put the filled pixel layer on top, just above the Merge Visible layer. That would work.

Murfee… Your method also seems to work. You must be better at math than all of us!

[Murfee]

Just now, smadell said:

You must be better at math than all of us!

😂 😂 

[Frozen Death Knight]

1 hour ago, Murfee said:

There is an easier way

• Sample the area that should be white
• Fill a new Pixel layer with the sampled colour
• Invert the filled Pixel Layer with the Ctrl/Cmd I keyboard shortcut
• Change the blend mode of the filled pixel layer to Colour Dodge

Thanks, that's exactly what I wanted! ^-^

Still, I made a feature request to add Divide to Affinity as well. Just to make things easier. 🥳

 

[Wosven]

For more flexibility :

• Add a fill layer and sample the colour you want
• Add an invert layer above
• Group those 2 layers
• Put the group in mode Colour Dodge

This way, you can add a mask if needed to lessen the effect on some parts of the image and modify the fill layer colour*

Edited March 30, 2020 by Wosven
* added main use of the fill layer

[Clau_S]

On 3/30/2020 at 10:19 PM, Wosven said:

• Group those 2 layers

Thank you! I was looking exactly to reproduce that tutorial. I was pretty sure that I could obtain the same result inverting the sampled color and applying another blending option, but as a novice in Affinity Photo I wasn't able to invert only the fill layer. I don't know why adding an adjustment as a child has no effect on fill layers. Grouping was the key.

 

For everyone else looking for color cast removal, the only missing part from the tutorial was to reproduce the behavior of the B slider in PS to bring back clipped details. If I'm not missing something (I can't exclude it), you cannot do it directly on Photo 'cause it uses an HSL method instead of the HSB. Raising the L (Lightness) value to the top brings the color to white, cancelling the effect. In HSB instead, raising the B (Brightness) value to the top, brightens the color to the maximum value allowed by hue and saturation. To keep it short, if you add and HSL adjustment  between the Fill layer and the Invert adjustment and check the HSV (which is the same as HSB) option, you can use the Luminosity shift as the B slider in Photoshop color panel. Raise it to 100% and you're good to go.

[Clau_S]

If someone is interested I've created a Macro to make the process faster.

After execution, you only need to pick the color from the appropriate area with the Color picker tool (I haven't been able to integrate this in the Macro) and set Solid color layer visibility back.

Color Cast Removal.afmacro