Scanning concepts
Most of VueScan’s settings fall into two groups, and understanding which group you’re in makes every other decision easier. This chapter explains that mental model, then covers the four concepts you’ll run into most often: resolution, bit depth, color mode, and output format.
The two phases of every scan
When you press Scan, VueScan does two distinct things in sequence:
1. Capture — the scanner physically reads the original.
These settings tell the scanner what to do. Once a scan is complete, the captured data is fixed — you can’t change a capture setting without scanning again.
- Source — which scanner to use
- Mode — Flatbed, Transparency, Document feeder
- Media — Color, Color negative, B/W text, Slide film, etc.
- Bits per pixel — how much tonal precision to record
- Scan resolution — how finely to sample the original
- Multi-sampling and Number of passes — read each pixel more than once for less noise
Almost all of these live on the Input tab.
2. Processing — VueScan transforms the captured data into the saved image.
These settings shape what to do with what was captured. They run against the raw data already in memory, so you can change them and re-save without re-scanning.
- Cropping — which part of the captured area to keep
- Color balance and white balance
- Filters — sharpen, descreen, restore colors, infrared dust removal, Touch Up
- Output color space — sRGB, Adobe RGB, ProPhoto RGB, etc.
- Output format and bit depth at save time
These live on the Crop, Filter, Color, and Output tabs.
Why this distinction matters in practice: if a scan looks wrong because of a processing setting (color, sharpening, format), use File | Save image to re-save with new settings — no need to re-scan. If a scan is wrong because of a capture setting (resolution too low, wrong Media type, ADF instead of flatbed), you have to scan again.
For the technical detail of what happens at each step, see How VueScan Works.
Resolution
Resolution is how finely the scanner samples the original, measured in dots per inch (DPI). Higher DPI captures more detail and produces larger files.
Rough guide:
| You’re scanning | Use roughly |
|---|---|
| Documents to read at original size | 300 dpi |
| Documents you’ll OCR | 400–600 dpi |
| Printed photos at original size | 300–600 dpi |
| Printed photos you may enlarge | 600–1200 dpi |
| 35mm slides and negatives | 2400–4000 dpi |
| Medium-format film (120) | 2000–3200 dpi |
| Large-format film (4×5 and up) | 1200–2400 dpi |
Optical vs interpolated. The optical resolution is what the scanner physically captures. The DPI dropdown often goes higher than the optical maximum — those higher values are interpolated, meaning VueScan or the scanner driver synthesizes extra pixels in software. Interpolated DPI inflates file size without adding real detail.
File size grows with the square of DPI. Doubling the DPI quadruples the file size for a given area. A 1200 dpi scan of a 4×6 photo is roughly 16× the size of a 300 dpi scan of the same photo.
For setting and changing resolution, see Choosing different resolutions.
Bit depth
Bit depth is how many discrete levels of brightness the scanner records per color channel.
- 8 bits per channel = 256 levels per channel = 16.7 million colors total. Standard for finished JPEGs and most everyday scans.
- 16 bits per channel = 65,536 levels per channel = trillions of colors. Useful when you’ll edit the image heavily later — much more headroom for shadow recovery, highlight pull-down, and white-balance shifts without visible banding.
VueScan always processes internally at 16 bits per channel, even when the scanner only delivers 10 or 12. The 8-vs-16 choice only matters at save time:
- 24-bit RGB TIFF or standard JPEG = 8 bits per channel.
- 48-bit RGB TIFF = 16 bits per channel — the right choice if Photoshop or Lightroom is the next stop.
- 64-bit RGBI TIFF = 16-bit RGB plus an infrared channel for later dust removal.
Higher bit depth roughly doubles file size at the same resolution. For the full bit-depth table, see File Formats.
Color mode and media type
The Media setting tells VueScan what kind of original is being scanned. It’s the single biggest determinant of how a scan turns out — more than resolution, more than color balance — because it changes the entire processing pipeline.
- Color — straight color reproduction. Photos, color documents.
- Color negative — invert the image, remove the orange film mask, restore color from the dyes.
- B/W negative — invert and convert to grayscale.
- Slide film — straight color reproduction tuned for slide gamma.
- B/W text — high-contrast monochrome, optimized for OCR.
- Image — capture and process exactly what the scanner sees, with no inversion or media-specific correction. Useful for unusual originals.
If a scan looks completely wrong (everything’s the wrong color, or text comes out muddy), the Media setting is almost always the first thing to check.
Output formats
The right format depends on what the scan is for. VueScan can save to several formats simultaneously — a common pattern is one TIFF master plus one JPEG for sharing.
| Format | Best for | Strengths | Trade-offs |
|---|---|---|---|
| JPEG | Sharing, web, photo libraries | Small files, universal compatibility | Lossy — quality degrades each time you re-save. 8-bit only. |
| TIFF | Archives, master copies, heavy editing | Lossless, supports 16-bit and infrared channels, optional LZW compression | Large files. |
| Documents, multi-page scans | Multi-page, searchable with OCR, universal | Less efficient than TIFF for image-heavy content. | |
| PNG | Documents with sharp edges, screenshots, line art | Lossless, smaller than TIFF for diagrams and text | 8-bit only; large for photographs. |
| JPEG XL | Modern web, archival photos | Smaller than JPEG at the same quality, supports lossless and 16-bit | Limited app support outside browsers as of 2026. |
| OCR text | Searchable documents | Plain extracted text alongside the image | Only useful when paired with another image format. |
| Raw TIFF | Reprocessing scans without re-scanning | Stores the unprocessed sensor data, including the IR channel | Very large files. Only useful if you’ll come back to the scan later. |
A few rules of thumb:
- JPEG for sharing, TIFF for archiving. Save both at once if you’re not sure.
- Use 48-bit TIFF if you plan to edit later. Editing an 8-bit file repeatedly causes visible banding; 16-bit gives you headroom.
- Use PDF for multi-page documents — keeps the document together as one file, supports searchable OCR, opens everywhere.
- Use raw TIFF if the scan is irreplaceable — a faded slide, a one-of-a-kind photo. You can always reprocess later with better settings or new VueScan features.
For the full list of supported formats, compression options, and bit-depth combinations, see File Formats.