Customer-supplied AI artwork is now a standing share of the files we receive, and it fails in patterns. Not randomly: the same three or four faults, over and over, because they come from how the tools work rather than from how carefully somebody wrote the prompt.
If you are decorating at volume, it is worth understanding which of those faults you can prompt your way out of and which you cannot, because the second group is where the reprints come from.
Only one of the three common faults is a prompting problem
Fault one: resolution. Not fixable by prompting. Image models emit at a fixed ceiling. Asking for maximum resolution does not raise it. In round numbers the current ceiling is about 1024 by 1792 from the mainstream chat tools and about 2048 from a Midjourney upscale.
Against a 300 DPI print requirement that gives you:
- 1024 px: clean to about 3.4 inches. Left chest, sleeve, pocket.
- 2048 px: clean to about 6.8 inches. A youth full front, a large left chest.
- 3300 px: clean to 11 inches. An adult full front.
No prompt closes that gap. An upscaler does, and modern AI upscalers work notably well on this kind of artwork because flat vector-like graphics have no film grain or optical detail to invent. Upscaling 4x on a clean graphic is routine. Upscaling a photographic AI image is where you start seeing invented texture.
The practical rule we use: decide the print width first, multiply by 300, and treat that as the minimum pixel width before the file is worth pressing. Working the other direction, generating first and hoping it is big enough, is how a design ends up approved at thumbnail size and soft at 11 inches.
Fault two: edge treatment. Fixable by prompting. This one is specific to DTF and it catches people who came from sublimation or vinyl.
DTF prints a white underbase beneath the color so the design stays opaque on a dark garment. The underbase is generated from the artwork's own alpha channel. Give it a hard edge and you get a clean print. Give it a soft edge, a drop shadow, an outer glow, or a feathered fade and the underbase carries that softness too, printing as a pale halo that reads as a mistake against the garment.
Every image model will add a subtle glow or shadow if you do not tell it not to. Tell it not to.
Fault three: lettering. Fixable, by not asking for it. Image models remain unreliable at type. They produce lettering that scans as correct and is not.
We can say that with numbers. Our own ready-made design library is 2,434 pieces, and when we described every one of them by eye we logged the artwork's spelling verbatim. The library contains PROUD PARTIOT, I DO'T ARGUE, STRIUE FOR PROGRESS, THE TEMPT FOR GREATNESS, and MADISON SQUARE GARDENS. Some of that predates AI, but it is exactly the failure mode these tools reproduce, and it is invisible until a customer reads the shirt.
Generate art without type, then set the type in vector. It prints sharper, it is spelled correctly, and it can be edited without regenerating anything.
The knockout trap
Ask a model for "a badge with the shop name inside" and it will frequently render the letters as holes in a solid shape rather than as ink.
That is a legitimate design choice, and on a garment it means those letters print as the garment color. On white blanks the text disappears entirely. We catch these on preflight, but it is worth spotting before you have quoted the job, because the fix is a redraw rather than a setting.
If you are checking a file quickly: open it over a mid-gray background rather than white. Knockouts and white-on-white artwork both become obvious immediately, and neither is visible against a white canvas.
Color
Image models work in sRGB and will happily produce colors that do not exist in a CMYK plus white ink set. Fluorescents and electric neons are the usual casualties: they render on screen and land noticeably duller on the garment.
If a specific neon is the point of the design, it is worth saying so at quote time. There are cases where we would tell you to run the job as screen print with a fluorescent ink rather than DTF, because the ink is the product and we cannot match it.
The prompt
Written to the constraints above rather than to the model's preferences. Replace the bracketed section.
Create the following artwork: [DESCRIBE YOUR DESIGN HERE] This will be printed via DTF heat transfer onto apparel. These are production constraints, not stylistic preferences. Follow them exactly. OUTPUT SIZE Generate at the maximum image dimensions and quality available to you. COMPOSITION Produce ONE standalone graphic on a single canvas. Center it with generous margin on all four sides. No part of the artwork may touch or be cropped by the canvas edge. BACKGROUND One flat solid color, fully uniform. Use a saturated magenta or a saturated green that appears nowhere in the artwork itself. No gradient, texture, noise, vignette, lighting, shadow, scenery, or color variation of any kind. This background exists only to be keyed out. EDGE QUALITY All exterior edges must be hard and cleanly defined. Do NOT apply drop shadows, outer glows, bloom, halos, feathered or fading edges, or any effect that blends artwork into background. Do not render a checkerboard or any simulated transparency. PROHIBITED OUTPUT No mockups. Do not place the design on a shirt, hoodie, hat, bag, mug, person, mannequin, wall, sign, poster, or product of any kind. No borders, frames, watermarks, captions, or annotations. Output the isolated artwork only. COLOR Solid saturated color. Avoid fluorescent and neon values, which fall outside a CMYK plus white ink gamut. Avoid very light tints adjacent to the background color. TYPOGRAPHY Include no text, letters, words, or numerals. Type will be set separately in vector. DETAIL Maintain clean line work. Avoid thin hairlines under roughly 1 pt at final print size, heavy noise, compression artifacts, and soft or fuzzy contours. Generate now at maximum available quality.
If the design genuinely requires the model to render lettering, add this and then proofread every character against the source:
If the design includes text, reproduce the following string EXACTLY, with no change to spelling, capitalization, punctuation, or spacing: "[EXACT TEXT]"
What we do on our end
Every file that comes to us gets checked for effective resolution at the requested print size, edge quality against the underbase, and knockouts that will vanish on the chosen garment color. If a file will not hold up, you hear about it before it goes on press, with what to change.
We would rather flag a file and delay a job by an hour than print artwork we know is going to come back.