You found the perfect photo of your grandmother as a young woman. You scanned it, uploaded it for colorization, and the result was... fine. Not great. The colors look muddy, the details are soft, and her face lacks the crispness you expected.

The problem is almost never the colorization. It is the scan.

AI colorization can only work with the information you give it. Feed it a low-resolution, poorly lit scan and you get a low-quality colorized image. Feed it a clean, high-resolution scan and the results are dramatically better.

The difference between a mediocre result and a stunning one often comes down to ten minutes of scanning preparation.

What Happens When You Scan Poorly

A colorization algorithm looks at every pixel in your image and makes decisions about what color it should be. More pixels means more information to work with. Fewer pixels means the AI is guessing with less data.

At low resolution, fine details disappear. The texture of fabric, the pattern on wallpaper, individual strands of hair, the lettering on a sign in the background. All of these help the AI make accurate color choices. When they are blurred into mush by a low-quality scan, the colorization has to make broader, less accurate guesses.

Think of it like describing a photo to someone over the phone versus showing it to them in person. The more detail they can see, the better their interpretation will be.

The Right DPI for Different Photo Sizes

DPI stands for dots per inch, and it is the single most important scanning setting for colorization quality.

Standard prints (4x6, 5x7): Scan at 600 DPI. This gives you more than enough resolution for colorization and prints up to 8x10.

Small prints (wallet-size, 2x3): Scan at 1200 DPI. Smaller originals need higher resolution to capture adequate detail.

Large prints (8x10 and bigger): 300 DPI is sufficient because the original already contains plenty of detail at that size.

Slides and negatives: Always scan at 2400 DPI or higher. These tiny originals need maximum resolution to produce usable files.

A common mistake is scanning everything at 300 DPI because that is the default on most scanners. For standard-size old photos, 300 DPI is not enough. Double it to 600 and you will see a noticeable improvement in your colorization results.

For a complete scanning walkthrough, see our guide to scanning old photos.

File Format Matters More Than You Think

Most scanners default to JPEG, which is a compressed format. Every time you save a JPEG, it loses a tiny bit of quality. That might not matter for a photo you are posting online, but for colorization, you want every bit of detail preserved.

Best choice: TIFF. Lossless compression, no quality loss. Files are larger but the quality is worth it. This is what professionals use.

Good alternative: PNG. Also lossless, slightly smaller files than TIFF. Works well for most purposes.

Acceptable: JPEG at maximum quality. If you must use JPEG, set your scanner to the highest quality setting (usually 100% or 12 on a 1-12 scale). The quality loss at maximum is minimal.

Avoid: JPEG at default quality. Default is usually around 80%, which introduces visible compression artifacts. These artifacts get amplified by colorization because the AI tries to interpret them as real image details.

Cleaning the Scanner Glass

This sounds obvious but it is the most overlooked step. A single fingerprint or dust particle on the scanner glass becomes a permanent artifact in your scan.

Before each scanning session:

1. Power off the scanner
2. Wipe the glass with a microfiber cloth
3. Use a small amount of glass cleaner if needed, but spray it on the cloth, not directly on the glass
4. Check the glass at an angle under a light to spot remaining smudges

Also clean the photo itself gently. A soft brush removes loose dust without damaging the print surface. Never use water or cleaning products on photographs.

Handling Curved or Warped Photos

Old photos often curl at the edges or bow in the middle. This creates uneven focus across the scan, which means parts of the image will be sharp and other parts blurry.

For mild curling: Place the photo face-down on the scanner and gently press the lid. The weight of the lid usually flattens it enough.

For stubborn curling: Place the photo under a heavy book for a few hours before scanning. Do not force a badly warped photo flat, as this can crack the emulsion.

For photos stuck in albums: If a photo is glued to an album page, it is safer to scan the entire page rather than risk tearing the photo trying to remove it. Crop the scan digitally afterward.

Color Settings for Black-and-White Photos

Here is a counterintuitive tip: scan black-and-white photos in color mode, not grayscale mode.

Why? Because old photos are rarely true black-and-white. They have warm sepia tones, cool blue tones, or subtle color casts from aging. Scanning in color mode preserves these tonal subtleties, which gives the colorization algorithm more information about the original image.

Scanning in grayscale mode discards this information and flattens everything to pure gray. You lose data that could have helped produce a better result.

Getting the Exposure Right

Most scanners let you adjust brightness and contrast before scanning. Use this feature.

For faded photos: Increase contrast slightly to bring out details that have washed out over time. Do not overdo it. A small boost is better than losing detail in the shadows or highlights.

For dark photos: Increase brightness by a small amount. Overly dark scans hide details that the colorization needs to work with.

For photos with even exposure: Leave the default settings. Only adjust if the preview clearly shows lost detail in shadows or highlights.

If your scanner has a histogram display, aim for data spread across the full range without clipping at either end.

Phone Scanning: When It Works and When It Doesn't

Not everyone has a flatbed scanner, and phone cameras have gotten remarkably good. Apps like Google PhotoScan and Microsoft Lens can produce decent results.

Phone scanning works for: Casual sharing, social media, and basic colorization of clear, flat photos in good lighting.

Phone scanning does not work well for: Photos behind glass, curved photos, photos in dim rooms, or any situation where you need maximum detail.

If you are serious about getting the best colorization results, a flatbed scanner is worth the investment. Basic models cost around thirty to fifty dollars and last for years. Libraries often have scanners available for free.

Which Photos Colorize Best?

Not all photos respond equally to colorization. High-resolution scans of sharp, well-exposed originals produce the best results. For a detailed guide on picking the right photos, see which photos work best for colorization.

In general, portraits with clear faces and distinct clothing give the most impressive results. Landscapes with sky, foliage, and water also colorize beautifully because the AI has strong reference points for those natural elements.

A Quick Checklist Before You Upload

Before running any scan through a colorization tool like PhotoRevive, check these boxes:

• Resolution is at least 600 DPI for standard prints
• File is saved as TIFF, PNG, or high-quality JPEG
• Scanner glass was cleaned before the session
• Photo is lying flat on the glass without curling
• Scanned in color mode, not grayscale
• No visible dust spots, fingerprints, or scanner artifacts
• Brightness and contrast are not clipping detail

Spending an extra five minutes on scanning quality saves you from disappointment with the colorization result. The AI is only as good as the image it starts with.

A great scan is the foundation of a great colorization. Get the scan right, and the color practically takes care of itself.

FAQ

What DPI should I use to scan old photos for colorization?

For standard-size prints (4x6 or 5x7), scan at 600 DPI. For smaller photos like wallet-size, use 1200 DPI. For large prints (8x10 or bigger), 300 DPI is sufficient. Higher resolution gives the AI more detail to work with.

Should I scan black-and-white photos in color or grayscale mode?

Always scan in color mode. Old photos have subtle warm or cool tones from aging that provide useful information for colorization. Grayscale mode discards this data and can produce flatter results.

Can I use my phone to scan photos for colorization?

Phone cameras work for casual use, but a flatbed scanner produces significantly better results for colorization. If you only have a phone, use a scanning app like Google PhotoScan and make sure you have bright, even lighting.