Making an RGB greyscale step-wedge?

[mjdl]

I must be exceptionally dense today, but I can't figure out how to make an RGB greyscale step wedge. I need the steps to be 2% in size, from 0% to 100% density; each patch must not very in density. The gradient transformation does not appear to give any method of automating that process. What am I missing? (aside from my brain)

[jsachs]

There are two ways I can think of the make a grayscale step-wedge. I don't use either of these methods - I write a program that generates the image directly, but if you want to use PWP you can use either of these two methods.

1) Use Layout to place the required number of patches on a background. Use the color picker to set the color of each patch.

2) Use Gradient to apply a custom color line which has a series of gray steps. If you start by creating a rough version of what you want and save the color line as a file, you can edit the file manually using Notepad to make the steps take on the values you want and make them spaced evenly.

[mjdl]

Ahhh! Thank you for reminding me of option 2: I'd forgotten that the colour line files are simple text files (BTW, that's a really good format choice for all such ancillary tool specification files, where the information stored can be expressed in a non-binary code, and one that PWP seems to have consistently chosen).

[tomczak]

If there is not too many steps in the wedge to make, you could apply Crop/Add Border a few times, switching input image to the most recent output, while adding a border of desired brightness each time you hit Apply. For 2%, that's 50 operations... probably too many... A workflow with 50 Crop/Add Border widgets may work (is there a limit on number of widgets in a workflow?).

Another method for up to 32 patches is to make a smooth, linear gradient from balck to white with Gradient, then use Posterize with Auto Palette - the 0% and 100% patches will be 1/2 of the width of the other patches, but you can extend them with Add Border. For 50 patches, you could use this operation twice then join the two halves with e.g. Add Border again.