Why Your Scanned Photo Looks Worse Than the Original

A scanned photo can look worse because of capture settings, scanner glass or light issues, the original’s position, compression, or simply how the preview is displayed. Start with the symptom: jagged edges point to resolution; white spots can point to dust; stripe patterns can be moire; and a preview may not show the same corrections as the saved scan. Rescan when the problem comes from capture, placement, or scan settings. Use later editing only after you have retained the best capture available.

There is no single documented percentage for how much each cause contributes to poor-looking scans. The available guidance identifies causes and remedies, but does not rank their frequency or weight.

Match the symptom to the likely scan-stage issue

Use this table as a diagnostic starting point rather than as proof of a single cause. Several documented issues can appear in one scan, and a rescan may be needed after changing the relevant condition.

Resolution: detail cannot be added by a higher saved number alone

If edges, lines, or fine details look jagged or rough, Canon advises increasing the scan resolution and scanning again. Its guidance describes resolution as the setting that determines the amount of image detail: a higher value captures more detail, while a lower value captures less.

Check whether a scanner lists optical resolution, interpolated resolution, or both. Brother defines optical resolution as the detail visible before software manipulation, while interpolated resolution is the resolution after software enhancement. The Library of Congress describes its preferred technical condition for digital photographs as the highest available resolution without rescaling or interpolation.

Recommended numbers differ because the cited guidance addresses different uses and standards. Canon lists 300 dpi for saving color photos to a computer and 150 dpi for web or email use, while advising a higher setting for enlarged printing. Epson lists 96–150 dpi for screen, email, or web use and 300 dpi for print or OCR, and says enlarging beyond the original scanned size always loses some quality.

Archival guidance is higher in some cases. NARA states a minimum of 400 ppi, measured to the source, for photographic prints and paper records with fine detail; the UK National Archives specifies 600 PPI for photographs. A separate Smithsonian standard uses a minimum target of 6,000 pixels on the long axis, with examples including 600 dpi for originals longer than 10 inches and 1,000 dpi for a 6-inch-long item.

These values should not be treated as one universal consumer setting. NARA, the Smithsonian, and the UK National Archives describe institutional digitization requirements, while Canon and Epson describe settings tied to intended use. The Library of Congress does not provide one numeric target in the cited statement, instead preferring the highest available non-interpolated resolution.

Jagged edges or rough fine detail: raise the scan resolution and make a new scan.
A larger print from the scan: use a higher setting than the cited consumer recommendations for ordinary computer storage or web use.
A file enlarged beyond its original scanned size: expect some quality loss, according to Epson.
A very large resolution figure labeled “interpolated”: distinguish it from optical resolution before treating it as captured detail.

Dust, dirty glass, light leaks, and poor contact with the scanner bed

White spots in the scan can come from dust on the document-table glass. Epson says to clean dirty scanner glass with a soft, dry cloth; for persistent material such as grease, it permits a small amount of glass cleaner on a soft cloth and says all liquid should be removed afterward. Epson also warns that damaged glass can reduce scan quality and says not to use alcohol, thinner, or corrosive solvents on the scanner.

Ambient light can create its own artifacts. Canon says that light entering between the document and platen can produce white spots, streaks, or colored patterns, and it advises covering the document with black cloth in that situation.

The original’s physical position also matters. Canon states that unclear or blurred text and lines caused by curved pages are not corrected by its correction feature. That is a reason to address placement and contact before expecting software correction to solve the blur.

Take care with the photograph itself. The Library of Congress cautions that even soft brushes can scratch or damage photographs and recommends an air bulb rather than canned air for loose surface dust. NARA separately advises a clean work area and routine cleaning of scanners, platens, and copy boards.

White dots: inspect and clean the scanner glass before rescanning.
White streaks or colored patterns near an edge: check for ambient light entering between the original and platen.
Blur associated with a curved original: reposition the original and rescan; Canon says that blur from curved pages is not corrected.
Loose dust on a photograph: the cited Library of Congress guidance favors an air bulb, not canned air.

Stripe patterns and screen appearance can be misleading

If the scan shows stripe patterns, moire is one documented possibility. Canon directs users to enable its Descreen or moire-reduction setting and scan again when moire appears, including when scanning a digital print photo. Canon also includes cleaning the platen and document cover in its scan-quality troubleshooting.

A small preview or a reduced on-screen view is not always a reliable quality judgment. Canon says image-correction results may not appear in the preview image, and it advises viewing at 100% because some applications do not display images clearly at a small display size. Epson describes its preview as a prescan and notes that its automatic mode shows a small preview after detecting a document or photo and selecting settings.

This does not establish that every soft-looking preview will produce a sharp final file, or that every soft screen view is harmless. It does establish that preview corrections and small display sizes can differ from the final viewing context, so inspect the saved file at 100% before judging it.

Stripe pattern or moire: use the scanner’s documented descreen or moire-reduction setting, then rescan.
Preview does not show an expected adjustment: Canon says correction results may not be reflected in the preview.
Image looks unclear only when viewed small: inspect it at 100% display size.

Phone captures: glare, tilt, and multi-frame processing

A phone photograph of a printed photo has a separate set of capture problems. Google’s PhotoScan guidance says not to tilt the phone while scanning, advises using flash to help remove residual glare and shadows, suggests moving to lower light if glare is excessive, and says to remove photos from sleeves or albums. For a photo in a glass frame, the same guidance says to turn on flash.

Google’s research explanation for PhotoScan describes a multi-frame method: moving the camera changes where glare falls, then aligned images can be combined to select image information from areas not covered by glare. The same explanation says glare in a single photograph can saturate an area, making the underlying part impossible to see or recover in that frame.

The product page describes automatic edge detection, perspective correction, smart rotation, and stitching multiple images to remove glare. Yet alignment quality remains relevant: Google’s research write-up says small misalignments can appear as duplicated image structures, with flow refinement used to reduce those artifacts.

A dedicated multi-frame scan method and a single phone photo are therefore not identical capture processes. The documented differences include multiple images for glare handling and automated boundary and perspective processing; they do not establish that every phone capture or every app result will be better in every setting.

Glare patch in a single phone photo: the cited Google research says saturated glare can hide the information beneath it in that frame.
Phone capture with tilted edges: keep the phone from tilting; PhotoScan also documents perspective correction.
Double-looking structures after multi-frame capture: Google identifies small alignment errors as a source of duplicated structures.

File format and compression: protect the best scan you have

A scan can lose quality after capture through JPEG compression and repeated saving. Epson says that higher JPEG compression lowers image quality, lost image-quality data cannot be restored, and quality deteriorates each time the data is saved. Its guide recommends TIFF when modification and retouching are required.

Institutional guidance is not completely uniform because preservation situations differ. The Library of Congress lists uncompressed files as a preferred condition and lossless compression or lower compression ratios as acceptable conditions. NARA recommends uncompressed TIFF production masters, while allowing consideration of LZW or ZIP lossless compression in an actively managed repository and not recommending JPEG compression inside TIFF.

The UK National Archives requires lossless compression for digitized records when the scanned image provides sole access, but permits lossy compression for digital surrogates when the original paper record remains the primary record; it gives a default 6:1 ratio for those surrogates. Separately, the Library of Congress format description notes that its Recommended Formats Statement includes JPEG/JFIF as a preferred format for photographs in digital form. These sources show that format choices depend on the declared purpose rather than supporting one unconditional rule for every copy.

Need to edit or retouch the scan: Epson recommends TIFF.
JPEG already saved repeatedly at high compression: Epson says lost image-quality data cannot be restored, so preserve the best available scan and avoid assuming later saving will recover it.
Need a preservation-oriented master: the cited NARA guidance recommends TIFF and uncompressed files, with LZW or ZIP lossless compression considered in an actively managed repository.

Decide whether to rescan or move on to restoration

Rescanning is directly supported when the problem is jagged detail, moire, dust-related white spots, ambient-light artifacts, curved-original blur, glare in a single phone frame, or a setting that did not capture enough detail. These are documented capture or setup conditions, and the cited scanner and phone guidance specifically calls for changing a setting, cleaning, covering, repositioning, or capturing again in several of these cases.

Before considering later restoration, keep the strongest available source file. The cited guidance supports checking the saved scan at 100%, separating optical from interpolated resolution, and avoiding unnecessary JPEG re-saves when image data matters. It does not support a claim that software can restore detail hidden by glare in a single saturated frame or blur caused by a curved original.

If the scan is already the best available capture and the remaining issue is within the image rather than the scan setup, review the available photo-restoration options. That choice should not be presented as a substitute for correcting documented capture-stage defects first.

Rescan first when the visible defect matches a documented capture issue such as dust, moire, ambient light, inadequate resolution, glare, or poor contact with the platen.
Inspect the actual saved file at 100% before deciding that a scan is unusable.
Avoid relying on an interpolated-resolution figure as evidence that extra original detail was captured.

Visible symptom	Documented cause or condition to check	Supported next check
Jagged edges or rough fine detail	Resolution is too low for the needed detail.	Increase scan resolution and scan again. (F10)
White spots	Dust on scanner glass can create white spots.	Clean the document-table glass as directed for the scanner. (F9)
White spots, streaks, or colored patterns	Ambient light can enter between the original and platen.	Cover the document with black cloth and rescan. (F13)
Stripe pattern	Moire can occur when scanning printed or digital print photos.	Use a descreen or moire-reduction setting and rescan. (F11)
Blur associated with a curved original	Canon says blur from curved pages is not corrected.	Address original placement and rescan. (F28)
Glare in a phone photograph	Glare can saturate parts of one frame; tilt and lighting are documented capture factors.	Avoid tilting, follow the documented flash and lighting guidance, or use a multi-frame capture method. (F20, F21)
Soft-looking preview	Corrections may not appear in preview, and small displays may look unclear.	Inspect the saved image at 100%. (F12, F14)
Quality declines after saving	Higher JPEG compression and repeated saves can reduce quality.	Keep the best scan and use TIFF when modification or retouching is required. (F16)

The table identifies documented conditions and checks, not the frequency or relative contribution of each cause. (F9, F10, F11, F12, F13, F14, F16, F20, F21, F28)

Frequently asked questions

What scan resolution should I use for old photo prints?

The cited numbers differ by purpose. Canon lists 300 dpi for storing color photos on a computer and advises higher settings for enlarged prints; Epson lists 300 dpi for print or OCR. For institutional digitization, NARA specifies at least 400 ppi for photographic prints and the UK National Archives specifies 600 PPI for photographs. The Library of Congress instead states a preference for the highest available non-interpolated resolution.

Why does my scan have white dots or streaks?

Epson says dust on scanner glass can cause white spots. Canon says ambient light entering between the original and platen can cause white spots, streaks, or colored patterns. Inspect the glass and the original’s contact with the platen before rescanning.

Can software fix a blurry scan?

The cited Canon guidance says that unclear or blurred lines caused by curved pages are not corrected. The cited Google research also says that glare-saturated areas in one phone frame can make the underlying information impossible to see or recover in that frame. Those cases support making a better capture when possible.

Why does my preview look different from the saved scan?

Canon says image-correction results may not be reflected in the preview image. It also says some applications do not display images clearly at small sizes and advises viewing at 100%. Epson describes its preview as a prescan, including a small preview in automatic mode.

Should I save scans as JPEG or TIFF?

Epson states that higher JPEG compression lowers image quality and that repeated saving deteriorates quality, recommending TIFF for modification and retouching. NARA recommends TIFF for production master files. The Library of Congress also records JPEG/JFIF as a preferred format for photographs in digital form, so the cited guidance does not make TIFF the only valid format for every purpose.

Related reading: photo restoration tool options

Why Does My Scanned Photo Look Worse Than the Original?