Getting Started
NextDither converts a source picture into a ZX Spectrum Next Layer 2 image - a .NX2 or .NXI file - ready for a NextDAAD game to load. This page takes you through opening a picture, seeing what NextDither did to it, and saving the result.
What you need
- The NextDither executable.
- A source image. The Open dialog's filter matches
png,bmp,jpg,jpeg,tif,tiffandwebpfiles, case-insensitively on the extension.
Opening an image
Choose File > Open and pick a file in the dialog. NextDither decodes it, converts it under the current settings, and shows both in the preview area. If the file cannot be decoded - a text file renamed to .png, for example - the toolbar reports the error in red and the app keeps running; nothing crashes on a bad file.
What the two panes show
By default the preview area is split into a source pane on the left and a result pane on the right. The result pane is what your exported file will contain. The source pane is not simply the file you opened - it shows the image after framing and the Adjust settings have been applied, at the same size and position as the result, so the two panes are actually comparable rather than showing different crops or aspect ratios. See preview for how to use this to judge dithering.
The stock preset is applied automatically
NextDither starts on a built-in preset named "NextDAAD Layer 2" - the toolbar reads Preset: NextDAAD Layer 2. It is compiled into the application rather than read from a file, and it is applied before you do anything else so that a freshly opened image already converts to settings that suit a NextDAAD game: 320x256, letterboxed and anchored to top centre, Floyd-Steinberg dithering, and palette slot 255 keyed to pure magenta so a painted hole becomes a transparent hole in the file. You do not need to set any of this up yourself to get correct output; the defaults exist so the tool is useful without configuration. Adjusting an image covers what each of these settings does and how to change them.
Saving
Choose File > Save As. Type a name in the native dialog and save it - the extension you type does not matter, because NextDither writes whatever extension each ticked export format actually produces. With the stock preset only the Bitmap format is ticked, so saving as cellar writes cellar.NX2 (or cellar.NXI if the frame is 256 wide). Ticking more formats in the Out tab writes more files alongside it - a .NX2.ZX0 compressed copy, a standalone .NXP palette, or an indexed PNG - all named after the same filename you typed.
The name you type in the dialog is what NextDither uses. The naming pattern in the Out tab's "Batch naming" section has no effect on Save As at all - that pattern only names the files a batch run writes.
A ZX0-compressed export takes a few seconds - measured at about 8.6 seconds for a 320x256 picture - so the toolbar shows a spinner and a "Saving cellar... compressing, this can take several seconds" message (naming whatever file is being written) while it works. The window stays usable and File > Save As is unavailable until the save finishes.
Where the file goes next
Drop the file NextDither saved straight into the game project's IMAGES\ folder. The authoring kit's build step (authoring-kit\lib\gfx.bat) stages an already-converted .NX2 or .NXI found there into RELEASE\ as-is - it never reconverts it - so this is the finished picture, not an intermediate one. The one exception is a title screen: that goes in the kit folder's root instead, saved as DAAD.NX2 or DAAD.NXI, not in IMAGES\.
The file's name matters here. The kit reads everything before the first dot as the picture's number, and a name that is not a plain number - up to three digits - fails the whole build rather than being skipped. NextDither keeps your source filename by default, so kitchen.png becomes kitchen.NX2 - not a number - and dropping that into IMAGES\ fails the build. Rename it to a number first, or see Batch conversion for how to make a batch run number its output automatically.