dmstraker

Nicely done, @smadell, and thanks for the InAffinity reference.
For a future version if you like, I keep a parallel web-based index (and resources) here: http://changingminds.org/disciplines/photography/affinity_photo/affinity_photo.htm

I am attaching a free PDF called “Affinity Photo from Ten Thousand Feet.” This is a 41 page book that explains many of the concepts and questions that forum members ask frequently.
Much of the information is based on presentations given to my local photography club. Some of it is based on a series of articles written for the club’s newsletter. Much of the book is newly written material, based on years of working to understand digital photography, how color works, and how Affinity Photo fits into that picture.
Please enjoy the book. All I ask in return is that you look it over and leave a comment.
Affinity_Photo_from_Ten_Thousand_Feet.pdf

Hi,
some time ago I found a post with free icons packs. Today I would like to share with you another 5 great libraries:
Evil Icons by evilmartians.com (1.9.0) / MIT license fontkiko (1.0.8) 521 icons x 3 (light, regular, solid) / SIL OFL 1.1 Phosphor Icons (v1.1.2) 683 icons x 5 (thin, light, regular, bold, solid) / MIT license Heroicons (0.4.2) 224 icons (outline, solid) / MIT license Boxicons (2.0.7) / ~1500 icons / SIL OFL 1.1 You can download them @ https://aiac.pl/affinity
Cheers,
Artur.

Should have gone to Specsavers
 

...and of course the corollary, to include a slider where there is now just a value box.
So: Add value boxes to 0-1 and -1 to 1 range variables, and sliders to real numbers and integers.
Thanks!!

You're welcome. Ta works. Also Diolch (Welsh).

Wow. Long conversation. I won't pretend to understand some of the discussions.
However something I haven't seen here is mention of the Erase blend mode.
A Pixel layer with Erase blend mode seems to work the same as a Mask layer, with Mask white=Pixel layer with  transparent, and Mask black=Pixel layer opaque. Non-pixel layers work in the same way. Coupled for example with Blend Ranges and inserted into a group (to limit the erase layer extent), it seems this could be of use at least in some applications.
Am I barking up the wrong tree (or just barking)?
Edit: Here's video:
 

Should have gone to Specsavers
 

Should have gone to Specsavers
 

Hey, this is by design.
An example of where this is useful is when we want to recolour stuff using say, a Pantone. I believe we do this when creating our workbooks. I agree it should probably be documented though.

This is a widely reported issue.
 

Definitely. I'm into Procedural Texture programming and would like to know more.
Aside: I program in PT using Excel -- one statement per line, comment in next column, then concatenate all lines to cut/paste to PT. Conditionals are a pain but doable.

Ping! Penny drops on what rgbtoi does -- luma values. Thanks. For convenience I sometimes refer to this as 361 - RGB approx 30%, 60%, 10%. Ballpark of course, thougn on-screen i found little discernable difference when picking 1% apart. It was an aha for me to discover the difference between HSL desaturation and Vibrance desaturation.
Don't know if this is relevant to the discussion, but a very quick way to do a very flexible pixel layer mask is to:
Duplicate layer or merge visible as desired. Add new pixel layer above. Group duplicated layer and pixel layer. Change blend mode of pixel layer to Erase. Add pixels by any method to the pixel layer (including partially transparent ones). Erase blend knocks out all pixels below but stops at the end of a group. It looks like it uses the inverse of pixel alpha, so adding pixels removes ones below.
I think that in this, only the alpha value of the pixel mask layer influences the mask effect, not luminosity calculation.
 

Thanks, @Max P. It's nice to have lots of functions though it would be nicer if the help system told us a bit more about what they do.

actually, out of curiosity I'm trying to document them on my own. Lots of googling, trial & error, and reverse engineering. We should start a new thread to collect all user-generated documentation.
 

Hi,
the help text displayed in the bottom line is missing relevant details and seem slightly misleading.
To set the origin, you need to double-click.
Click alone has no effect. Click AND drag (not click OR drag) will drag the point of origion.
Recommendation for help text:
Double-click to set origin, or click-drag to move origin.
 
Help documentation / persistent variables
The procedural texture help documentation could be improved, e.g. by adding a chapter to list all available "persistent variables" and their definitions.
ox and oy is currently not mentioned at all in help (only listed in the UI bottom line)

The values have been investigated by trial & error. It would be great to get them confirmed or corrected by the devs.
 
 

Hi,
 
looking for a more in depth documentation about functions in procedural texture and equations filters.
The table in the help file provides mostly the names and parameter list, lacking more detailed definition.
Using the forum seach, help search, and finally google to find more did not revale useful results, as names are often generic and used in other contexts, e.g. try tocui
https://affinity.help/photo/en-US.lproj/index.html?page=pages/Filters/filter_equations.html?title=Equations
Here are my questions:
Where can i find the complete definition of the functions? Where can i find a complete list of "persistent variables" like h,w, R,G,B,A, I, x,y ? The scope where these variables exist, e.g. color format like RGB / GRAY / LAB, equations or procedural text filter, ... Thank you in advance.

Many thanks @NotMyFault! Do you know of any source where I can find more about other hardly-documented functions?

Hi dmstraker
  Take a color in Hex, and extract componant in decimal,  [0....255]
   if i remenber well
Hex: #fed33c  rgb(254,211,60)
The help say
rgbtoi   use  rgbtoi(S r, S g, Sb) or rgbtoi(V rgb)     

Hi Max,
 
i just checked, rgbtoi uses ITU-R 601 for conversion
 
Y′=0.299R′+0.587G′+0.114B′{\displaystyle Y'=0.299R'+0.587G'+0.114B'}   by measuring (info panel) the result for a full red/green/blue pixel. These values match within the limits

Hi @Max P Yes, that's the one. I'm tinkering with a Procedural Texture macro for it, which may appear some time on my YouTube InAffinity channel. Conversion is easy enough (using easyrgb website algorithm for RGB to and from HSV).  Current puzzles include what to do when you change a value -- eg increasing W, do you compress B and/or central hue region.
https://www.easyrgb.com/en/math.php

Hi NotMyFault
 
Thank take  time for answer to me
I' m not a professionnal
I'm just a retiree who has time to explore some solutions,
in fact my interest is more, the ability to mix transparent images, shots of images included in vector shapes in a plane, an image wider, possibly with a z depth. ( Affinity, Open GL?, blender?).
In fact I use less and less mask but more and more layers in Erase mode, with paintbrush with modultation opacity
Well I'm not going to waste you more time thank you again
 
 

I do a fair amount of Procedural Texture programming and handle conditional statements by such as first deriving 0-1 for true-false and then multiplying by the result for condition a then adding multiplying by inverse for condition b. For comparing numbers, I typically subtract and do a roundup (scaling numbers as needed).
eg (untested, so fingers crossed) a version of max(R,G) is:
var ifrg=roundup(R-G); //is zero if green greater than red else 1
var mxrg=ifrg*R+(1-ifrg)*G;
And yes, things get complex!
 

Hi Dave, yes, was a bit disappointing—the low resolution was compounded by a decision to frame everything in a window surrounded by graphics. The resampling was very poor so UI text ended up illegible. Tomorrow should hopefully address these issues as I believe the presentation will at least be full screen, and possibly streamed at 1080p.
The two pre-recorded evening sessions will certainly go up on YouTube—for the two live sessions, I may well record versions of these to upload as well...

...and of course the corollary, to include a slider where there is now just a value box.
So: Add value boxes to 0-1 and -1 to 1 range variables, and sliders to real numbers and integers.
Thanks!!