Erich Campbell tells you everything you need to know about digitising file types
Even those with a basic understanding of embroidery know that machines require a file to stitch a design. However, there are different types of files and not everybody has a clear understanding of what they are and what they do. In this month’s column I’ll be taking a look at the files generated by the digitising process and why those file types matter to your embroidery operation.
What’s in a file?
There are two main types of digitising file – the ‘working file’ and the ‘stitch file’.
These are, unsurprisingly, the files in which a digitiser works. These entirely proprietary, software-specific files contain any imported art, shapes a digitiser draws, and the stitch types, angles, density, and other settings used to fill those shapes with stitches. They can be edited and resized, with the software using the parameters set by the digitiser on each vector-like embroidery object to generate the actual stitches in the file that’s output for the embroidery machine. Embroidery machines do not read working files.
Looking at a simple object in the working file, the hat brim, you can see that despite it being a fairly complicated shape, it renders well as a curved fill using just one object and a line denoting the fill curve
When working in digitising software on a working file, you edit objects by grabbing those same nodes, handles, curves and angles created in digitising the element.
This means that altering a shape, like making this satin stitch wider on the right side, would only require moving eight points, and changes to things like stitch type, length or automatic underlay style, would only require a setting to be changed in the object’s properties.
Stitch editing – something you might be forced to do when trying to rework a stock design from a stitch file, for example – requires the end point of each stitch to be moved manually. Moreover, changes like density alterations or underlay styles would require the addition or subtraction of stitch points, one at a time, and in sequence with the existing stitches
These files are exported from the working file and are the most common type of file purchased as stock designs or delivered by digitisers. The working file’s shapes and settings are interpreted into a set of individual stitch coordinates and machine commands and exported into a format that a specific embroidery machine can read. Proprietary stitch file types exist, but the most used format – .DST – is readable by any machine. Most stitch files can be converted from one format to another in basic software without significant alteration. Output stitch files can’t be easily edited or resized – generally, they contain only stitch coordinates and machine commands, losing the shapes created in the working file and the prescribed settings attached to them. Moreover, they may not even contain colour information, having only ‘colour stops’, which indicate to the machine when it’s time to switch needles.
Examining the same simple shape as reprocessed from the stitch file shows 20 objects where there originally was one. Moreover, many of these objects no longer have addressable settings as they have been rendered as individual groups of manual stitches. Selecting the centre section reveals that the only way to edit this area of the object is to move individual stitch endpoints, even after reprocessing. Unfortunately, without the original working file, anyone who wants to make a simple change to the shape of the object, the curve of the fill, the stitch length, or the like would be better off recreating the object from scratch
Opening the stitch file, the software attempts to process the stitches back into working file shapes, but as the object list on the right shows the nearly 300 drawn objects have been interpreted into 622 objects on re-import. This means that many objects are split into multiple pieces and it’s very likely that things like automated underlays and lock stitches have been processed into manual stitch objects in this version of the file
There is some software that is used to process stitch files and ‘guess’ at the vector-like objects created in their working file, but it is rarely very effective. Without ‘processing’ or software that’s able to interpolate/remove stitching directly, stitch files cannot be resized without increasing or decreasing density, altering stitch length and texture, potentially creating overly long or short stitches, and/or making details either too dense or sparse. You are able to import stitch files into digitising software to add text or combine designs into one decoration area, but any significant alteration of the basic shapes, settings or sequence requires the original working file and must be done in the same software in which the design was created.
The easiest metaphor to grasp is that working files are to vector graphics what stitch files are to raster graphics exported from a vector graphic. You can create a graphic as a vector, drawing shapes and assigning colours, and then export that graphic to a JPG or PNG file. Though you could add elements over that image or potentially process it, if you want to change the shapes you created in your original art, you’ll need the original vector file. Similarly, auto-tracing, which creates a new vector file from a source raster image, renders files that are noticeably less ‘clean’ than the original source.
In my working file for this emoji design, you can see the backdrop that belongs to the original artwork I used to create the design. Notice, too, that the individual objects drawn for the design, with their properties, are available in the objects tree on the upper right hand side. On the lower right, the settings for this particular object can be seen and altered. In the design page, you’ll see that with the fill object that defines the crown of the hat selected, the vector outline is shown with the handles ready for editing the curves. Moreover, the curve that is used to define the curve in the fill stitch is there for alteration. In the working file you can alter and scale the design, and the software will process the resulting changes into stitches that match the parameters set in the object properties
When looking at the stitch file, you might at first not see any difference, but a quick glance at the object panel shows that only the colour stops are available to select separately. Any alterations to this piece would have to be done one stitch at a time, or at least by moving selected stitch endpoints. In the lower right properties pane, none of the original settings are present, nor can the parameters of the design be altered
Classic stitch file formats, such as the ubiquitous DST format, may not store colour information, meaning that opening these formats in any software will display them in the default palette native to the software
Which file type(s) do you need?
Ultimately, many embroiderers never digitise nor edit embroidery files. If you prefer to leave that to punchers like myself, the stitch file (coupled with a colour sequence document) will suffice. If you intend to rework designs, compensate for wildly different substrates, or even edit text in-house with ease and efficiency, the working file is desirable if not essential. If you never intend to go further than adding surrounding text or changing the orientation of a design, simple compositing software with functions for type and basic stitch files is likely to be all you’ll need for most applications.
The working file has 132 objects, and the fourth colour is a single small crescent of shading fill, here rendered from a single object
Here you can see the finished Super Strypi logo sample, rendered on a cotton piqué polo swatch
In this reprocessed file created from a stitchfile, the number of objects has ballooned from 132 to 316. Also, on the simple crescent shape that was selected in the working file example, the object has been split into three pieces, with the bottom third of the crescent rendered as manual stitches, making it possible to change settings only on a portion of the object. This file type maintains thread colours, but for editing/ alteration, you’ll find many of the objects altered enough that they are unable to be changed/altered without extensive redrawing and/or clean-up
Erich Campbell is an award-winning digitiser, embroidery columnist and educator, with 18 years’ experience both in production and the management of e-commerce properties.He is the programme manager for the commercial division of BriTon Leap.