double jacquard wish list - double-height DBJ

[sandrina2]

separation could be used for single color work and for multiple colors as well

[Adrienne200]

This is picking up where I left off in #239, other ways of doing DBJ.
2-color:
The version already implemented is the best and most standard way (just needs the tweak to select white first)
The first pair of diagrams here show a double-height 2-color DBJ, also useful.

3 or more colors:
The version already implemented is good, it's one of the classic ways of doing 3 color DBJ.
The version shown in sandrina2’s lower set of pictures here is another common way.
It is also often done by starting with the rows one pixel high, and letting the software double-height it for you. So the sample would start like this, and knit up the same as above.

Though I think I'd have made it knit the yellow first. In this example there's very little difference between foreground and background, but I'm assuming that if you were going to knit this your actual pattern would be yellow -> white, red -> gray and blue -> black. When drawing descriptive diagrams like these it's useful to assign a color to the background. But in real use it will be white, and should be knitted first to conform to what most people expect. Then I think the shades of gray come next, with black last.

There are other ways of doing 3-color DBJ such as the heartofpluto version, we can leave that for later. I have done some work on understanding it and describing how it works, I'll post it soon.

[dl1com]

Is this the same topic as #239?
Please try to stay in a single issue when discussing on the same topic, so we have everything in a single place.

[sandrina2]

I had missed the other post, will try to be more mindful. Not every pattern can be knit using the default separations in either method and vice versa. Sometimes the only way to get things to work is to change the sequence of colors for segments of the repeat (or your starting colors) which can get really tricky without prompts and planning. The separation can be used to knit fabrics other than DBJ. I have also been a long term Passap knitter, where this method is the default, and was interested in interpreting the fabrics for Brother knitting without doing the separations by hand first.

[Adrienne200]

As we have two separate DBJ methods being requested, and two open issues on this topic, let's use this one for the method being discussed here where each row is double-height, and discuss the heartofpluto method over in #239.
Each color/stitch is knitted twice, once left-right, and the same needles again right-left. Then the gaps are filled in with the next color, and the next until two complete identical rows have been knitted.
Birdseye on the ribber throughout.
It needs a pre-select setup row, more on that in a moment. Here's how it works once it gets going:
Color 1:
Pass 1 L-R: Knits row 1 Color 1 on main bed, selects for Row 1 Color 1 again
Pass 2 R-L: Knits row 1 Color 1 on main bed, selects for Row 1 Color 2
Color 2:
Pass 3 L-R: Knits row 1 Color 2 on main bed, selects for Row 1 Color 2 again
Pass 4 R-L: Knits row 1 Color 2 on main bed, selects for Row 1 Color 3
Color 3:
Pass 5 L-R: Knits row 1 Color 3 on main bed, selects for Row 1 Color 3 again
Pass 6 R-L: Knits row 1 Color 3 on main bed, selects for Row 2 Color 1

Result: two rows the same on the front, 3 birdseye rows on the back
Pass 6 sets things up for Pass 1 of the next set of 6 passes.
It can be extended to 4 or more colors, but the floats become difficult after about 4.
How would the pre-select work? The selection is the same as pass 6, but without setting all the buttons to DBJ yet. But pass 6 is right-left. One way would be to make AYAB able to start from the right, issue #247. Is there any other way to do it, such as a free pass row?
The above assumes that the image is provided in single-height, and the software does each of the given rows twice, giving a double-height result.

The other way to do this is to provide the image already in double-height, in which case it would look like this:
Setup row: Preselects for Row 1 color 1.
Color 1
Pass 1 L-R: Row 1 Color 1 on main bed, reselects for Row 2 Color 1
Pass 2 R-L: Row 2 Color 1 on main bed, selects for Row 1 Color 2
Color 2
Pass 3 L-R: Row 1 Color 2 on main bed, reselects for Row 2 Color 2
Pass 4 R-L: Row 2 Color 2 on main bed, selects for Row 1 Color 3
Color 3
Pass 5 L-R: Row 1 Color 3 on main bed, reselects for Row 2 Color 3
Pass 6 R-L: Row 2 Color 3 on main bed, selects for Row 3 Color 1

BTW, this is the same sequence that is needed for single-bed 3-color work, as discussed in #204

[Adrienne200]

This is a standard way of doing 3+ color DBJ that users are sometimes surprised doesn't yet exist in AYAB. See my description just above, on Jun 6th, 2018. I think I prefer the first variant, where the image is provided with each row appearing just once, and the software effectively double-heights it and knits it twice, across and back.