Effective DPI and resolution warnings

Summary

Effective DPI measures how sharp a placed image will print at its current size on the artboard — calculated from the image's pixel width divided by the layer's width in inches. Below 150 DPI, the layer's Transform panel shows a red LOW badge and a resolution warning.

Use it when

• You want to know whether a placed image is high-resolution enough to print sharply at its current size.
• You're deciding how large you can safely scale an image up.
• You see a red DPI warning and want to understand exactly what it means.

Before you begin

Select a placed image layer — effective DPI only applies to images, not shapes, paths, text, or templates (confirmed: a shape layer's Transform shows no DPI readout at all).

Steps

1. Select an image layer and open Transform.
2. Read the DPI readout, shown just below the layer's size and rotation.
3. If it's below 150, a red LOW badge appears next to it, with a Resolution note explaining the consequence.
4. To raise the effective DPI, make the layer smaller (reduce W) — the readout updates live as you resize.

What changes

• Effective DPI is calculated from the image's native pixel width divided by the layer's current W, in inches — confirmed directly: the demo art (2048 px wide) at a 21.33 in layer width read 96 DPI (2048 ÷ 21.33 ≈ 96), and changing W alone to 13 in raised it to 158 DPI (2048 ÷ 13 ≈ 157.5).
• Changing the layer's H alone, independent of W, did not change the DPI readout at all — DPI tracks width only, not height or the smaller of the two dimensions.
• The readout updates live as you type a new W and commit it — no separate refresh or reselection needed.
• Below 150 DPI, the badge changes from plain text to a red dl-badge dl-badge--danger style with a —LOW suffix, plus a Resolution note: Below the 150 DPI print-quality minimum — the print may look blurry or pixelated at this size. At and above 150 DPI, neither the badge styling nor the note appears — there is no intermediate "caution" tier.

Print note

Effective DPI is exactly what it sounds like: an estimate of your actual print sharpness at the current size, not a preview-only number. It reflects real pixel density, so treat the LOW warning as a genuine signal that a printed copy may look soft or blocky at that size — not a placeholder value like the grid spacing or color-profile notices elsewhere in the app.

Warnings and limits

• The rounded DPI number can be misleading right at the 150 threshold. Testing found two different layer widths that both displayed as 150 DPI in the readout — one (the true value just above 150) showed no warning, the other (just below 150) showed the full LOW badge and note. The displayed whole-number DPI is rounded for display; the pass/fail check uses the precise, unrounded value. Don't assume a displayed 150 DPI means you're safely at or above the threshold — check whether the LOW badge is present, not just the number.
• There is no way to see effective DPI for anything other than a single selected image layer — it is not part of a whole-artboard or multi-selection summary here (a global check exists separately in Review production readiness, covered in the Output chapter).
• Because DPI is driven by W only, an image that has been resized very tall and very narrow (or vice versa) can carry a DPI reading that doesn't intuitively match how large it looks on screen — check the actual W value if a DPI reading seems surprising.

Desktop and mobile

The DPI readout, the LOW badge, and the Resolution note are reachable the same way on desktop (inline in Transform) and mobile (the Adjust sheet from the bottom bar) — all three were confirmed present in the mobile sheet for a placed image at native size.

Troubleshooting

Related topics

• Crop and framing
• Contrast, black point, white point & gamma
• Place vs. Fill canvas
• Production readiness

Verification note

Verified against Blotter Builder on 2026-07-20.

Source notes

Primary observations — all from the live application at https://blotterbuilder.tdl.fyi, 2026-07-20, using the demo artwork (2048 × 2048 px) placed via Place image.

• Observed — at native placement (W 21.33 in), the readout showed 96 DPI with a red 96 DPI—LOW badge and the resolution note.
• Observed — setting W to 13 in (leaving H at 21.33 in) changed the readout to 158 DPI with no LOW badge.
• Observed — subsequently changing H to 5 in, with W still 13 in, left the readout at 158 DPI — unchanged, confirming height does not factor into the calculation.
• Observed — boundary-tested the threshold: W 13.653 in (precise DPI ≈ 150.05) showed 150 DPI with no LOW badge; W 13.667 in (precise DPI ≈ 149.85) also displayed 150 DPI but did show the red 150 DPI—LOW badge and note — the same rounded display, opposite pass/fail outcomes.
• Observed — the LOW badge's computed styles: class dl-badge dl-badge--danger, text/border color rgb(229, 72, 77) (red), versus the plain DPI readout's rgb(242, 240, 233) (the app's standard off-white text) with no badge styling.
• Observed — at W 3 in, the readout showed 683 DPI with no LOW badge, confirming high-DPI values show as plain text only, with no distinct "good" indicator beyond the absence of the warning.
• Observed — a Shape layer's Transform panel showed an empty string where the DPI readout appears for images — no DPI concept applies to vector layers.
• Observed — at 390 × 844, selecting a native-size placed image and opening the Adjust sheet showed the DPI readout, the LOW badge, and the resolution note, matching desktop.

Verification log