Keep three values separate
Pixel dimensions describe the stored image grid. A resolution tag describes an intended relationship between pixels and physical units. A layout describes the physical rectangle where the image will be placed. These values can be related without being the same thing.
For example, a 3000 × 2000 image corresponds to 10 × 6⅔ inches at 300 PPI. At 150 PPI, it corresponds to 20 × 13⅓ inches. If only the tag changes, both versions still contain 3000 × 2000 pixels. The larger suggested print spreads those pixels over more area.
Resampling changes the grid
An operation that changes the actual pixel dimensions is different. Resampling can remove samples or calculate additional ones. Increasing the number of pixels does not establish that the file now contains newly captured scene detail; it describes a new grid computed from the available image.
PrintLilt’s default raster export uses the retained source pixels rather than silently enlarging them to meet an arbitrary PPI target. The target physical size is a calculation and layout choice. It is not an instruction to invent a higher-resolution original.
Browser exports have metadata limits
Browser canvas export does not preserve every piece of the original file’s metadata. The documented canvas export behaviour uses a 96-dpi resolution value for formats that encode such a field. A downstream application can therefore display a resolution label that differs from the effective PPI of your intended print.
Read the downloaded pixel dimensions and specify the intended print size explicitly. A 2400 × 3000 image placed at 8 × 10 inches is 300 PPI regardless of a different default-size suggestion in another viewer. Do not interpret that viewer’s label as a new measurement of captured detail.
A PDF expresses physical placement
A paper-layout PDF defines a page and an image rectangle in physical units. That makes it useful when the requirement is an eight-inch photo on a particular sheet with known margins. The raster image inside the PDF still has a finite number of pixels.
The print dialog can nevertheless scale the entire PDF. A Fit setting may shrink it to the printable area. Use actual size or the equivalent 100% option, match the paper, and measure a calibration mark if the dimensions must be reliable.
Check the right thing after export
For a photo export, inspect pixel width, pixel height, orientation, crop, and background. For a layout PDF, inspect page size and physical photo placement. For a project JSON file, remember that it stores settings and source-file information rather than a new photo.
Keep the original when its camera information or original metadata matters. The exported result is a separate derivative for the chosen task. Repeatedly changing a DPI label is not a substitute for preserving the source, choosing a sensible crop, or checking the physical print.