Comparing two photographs of a person taken several years apart can be surprisingly difficult. Aging, weight changes, hairstyle, facial hair, expression, lighting, camera angle, image resolution and even the camera lens can make the same face appear substantially different.

Conversely, two different people may share several common facial characteristics.

For this reason, a responsible facial comparison should not be based on an overall impression such as "these two people look alike." Instead, photographs can be examined systematically for visible similarities and differences among individual facial features.

In professional facial-image examination, one important approach is morphological analysis. Current facial-comparison guidance describes morphological analysis as evaluating correspondence among facial components and their characteristics, including their presence, shape, appearance, symmetry, location and relative proportions.

This article explains how a person can perform a non-conclusive visual comparison of photographs taken at different times.

Important: Visual similarity alone should not be treated as proof that two photographs depict the same person. High-stakes identification should be performed using appropriate professional procedures and corroborating evidence.

1. What Is Facial Photograph Comparison?

Facial comparison involves examining facial images to identify visible similarities and differences.

A systematic comparison may consider:

• Overall face
• Forehead
• Hairline
• Eyebrows
• Eyes
• Nose
• Cheeks
• Mouth
• Lips
• Chin
• Jaw
• Ears
• Relative facial proportions
• Scars, marks or other visible characteristics

Professional guidance identifies morphological analysis, superimposition and photo-anthropometry as facial-comparison methods, with morphological analysis described as the primary approach.

The goal of a basic visual exercise should therefore be:

Observe → Compare → Document

rather than:

Look → Guess → Declare a match.

2. Start With Image Quality Before Comparing Faces

Before examining facial features, evaluate whether the photographs are actually suitable for comparison.

This is critical because facial-comparison quality depends heavily on the information visible in the images. Factors including resolution, lighting, focus, pose, angle, orientation and obstruction can affect what can reliably be compared.

Check the following:

Resolution

Can you clearly see:

• Eyelids?
• Eyebrow edges?
• Nose tip?
• Nostril shape?
• Lip boundaries?
• Chin?
• Ear structures?

A photograph containing only a few pixels across an important feature cannot provide reliable fine-detail information.

Focus

A high-resolution image can still be useless if the face is out of focus.

Lighting

Uneven lighting can:

• Make one cheek appear larger
• Hide an eyelid
• Change apparent nose width
• Create artificial jaw definition
• Hide scars or marks

NIST testing also notes that poor photography and illumination can affect facial-recognition performance.

Head orientation

Ideally compare:

frontal photograph ↔ frontal photograph

rather than:

frontal photograph ↔ 30-degree side photograph

Expression

A neutral expression is preferable.

Smiling can change:

• Cheek position
• Eye opening
• Mouth width
• Lip thickness
• Jaw appearance

3. Do Not Compare Only the Overall Face

One of the easiest mistakes is saying:

"The faces look similar."

This is too subjective.

Professional morphological approaches instead break the face into individual components and characteristics.

A useful comparison sequence is:

Face → Forehead → Eyebrows → Eyes → Nose → Cheeks → Mouth → Chin → Jaw → Ears → Distinctive characteristics

Each should be examined separately.

4. Overall Face Shape

Begin with overall facial geometry.

Consider whether the face appears:

• Long or short
• Narrow or broad
• Oval
• Rectangular
• Rounded
• Tapered toward the chin

Instead of simply writing:

"Both have oval faces."

a better observation might be:

"Both photographs show a face that appears longer than it is wide, with gradual narrowing toward the lower face."

This records observable morphology rather than relying entirely on a category label.

Professional guidance specifically cautions against relying on simplistic classification schemes alone because they can create differences between observers.

5. Forehead

Compare:

• Forehead width
• Apparent height
• Temple shape
• Side contours
• Relationship between eyebrows and hairline

However, forehead appearance can change substantially because of:

• Hairstyle
• Hair loss
• Camera angle
• Head tilt

Therefore, forehead observations should generally be combined with other characteristics.

6. Hairline

The hairline can sometimes provide useful visual information, particularly when photographs are relatively close in age.

Examine:

• Central hairline
• Left temple
• Right temple
• Widow's peak if visible
• Recession pattern
• Asymmetry

Do not give excessive importance to hairline appearance across photographs separated by many years because aging and hair loss can change it considerably.

7. Eyebrows

Eyebrows can provide useful morphological information.

Compare:

• Thickness
• Length
• Curvature
• Inner ends
• Outer ends
• Distance from eyes
• Spacing between eyebrows
• Relative height
• Asymmetry

For example:

Characteristic	Photo A	Photo B
Thickness	Thick	Thick
General direction	Mostly straight	Mostly straight
Central spacing	Narrow	Narrow
Outer taper	Present	Present

Remember that eyebrows can also be trimmed, shaped or altered.

8. Eyes

Do not compare only eye colour.

Instead examine:

• Eye opening
• Shape
• Relative size
• Spacing
• Upper eyelid
• Lower eyelid
• Inner corners
• Outer corners
• Relative alignment
• Eyelid exposure
• Natural asymmetry

Eye spacing

A useful proportional observation is:

distance between the eyes relative to the width of the face.

Absolute pixel measurements from two differently sized photographs are not directly comparable.

9. Nose

The nose is an important region for morphological comparison because several structural characteristics may be visible.

Examine:

• Bridge length
• Bridge width
• Bridge contour
• Nose projection
• Tip shape
• Tip width
• Nasal base
• Nostril shape
• Nostril orientation
• Relative symmetry

Rather than saying:

"Both noses are the same,"

record observations individually:

Bridge: similar apparent length
Tip: somewhat different
Nasal width: broadly similar
Nostrils: insufficient detail

This is more transparent.

10. Mouth and Lips

Examine:

• Mouth width
• Upper lip thickness
• Lower lip thickness
• Cupid's bow
• Lip curvature
• Mouth corners
• Upper-to-lower-lip relationship
• Distance between nose and upper lip

A particularly useful observation may be a relationship rather than an absolute measurement.

For example:

In both photographs, the lower lip appears fuller than the upper lip.

11. Chin

Compare:

• Chin width
• Chin length
• Projection
• Roundness
• Squareness
• Central indentation
• Relationship with lower lip

Chin appearance can nevertheless be affected by body weight, head position and camera perspective.

12. Jawline

Compare:

• Jaw width
• Jaw angle
• Taper toward chin
• Left-right symmetry
• Lower-face proportions

Be particularly cautious when photographs were taken many years apart.

The jaw and surrounding soft tissue can look different because of:

• Aging
• Weight gain
• Weight loss
• Muscle development
• Facial fat redistribution
• Head position
• Lighting

A different-looking jaw therefore should not automatically be interpreted as evidence that two images depict different people.

13. Cheeks and Cheekbones

Examine:

• Cheek width
• Cheek fullness
• Cheekbone prominence
• Left-right symmetry

These are comparatively vulnerable to changes in:

• Weight
• Age
• Nutrition
• Muscle/fat distribution
• Expression

Treat cheek similarity or difference cautiously.

14. Ears

When sufficiently visible, ears provide several characteristics that can be documented.

Look at:

• Overall size
• Projection
• Upper contour
• Helix
• Antihelix
• Earlobe
• Attachment
• Relative position

Do not simply record:

"Large ears."

A more informative observation would be:

"Both images show ears projecting outward from the sides of the head, but fine internal ear anatomy cannot be compared because of image resolution."

15. Facial Proportions

Proportional analysis can help organize a comparison.

Useful relationships include:

Face Length-to-Width Ratio

Compare apparent:

facial length ÷ facial width

between photographs.

Inter-Eye Proportion

Compare:

distance between eyes ÷ face width

Nose-to-Face Relationship

Compare:

nose length ÷ face length

Mouth-to-Nose Relationship

Compare:

mouth width ÷ nose width

Vertical Relationships

Examine approximately:

Hairline → eyebrows → nose → mouth → chin

The important principle is to use relative proportions, not raw pixel counts from differently scaled photographs.

16. Facial Asymmetry

Human faces are naturally asymmetric.

Look for consistent asymmetries such as:

• One eyebrow sitting higher
• One eye appearing more open
• Slight nasal deviation
• Unequal mouth corners
• Unequal ear projection

But pose and perspective can create false asymmetry, so these observations require comparable head orientation.

17. Scars, Moles and Other Distinguishing Characteristics

Potentially informative visible characteristics include:

• Scars
• Moles
• Birthmarks
• Permanent skin marks
• Unusual ear characteristics
• Facial asymmetry

Professional morphological guidance includes discriminating characteristics such as scars, marks and tattoos among potentially examinable characteristics.

However, absence of a mark in one photograph does not necessarily mean it was absent. Lighting, makeup, compression or insufficient resolution may simply hide it.

18. Understand How Aging Changes Facial Appearance

This becomes especially important when comparing a photograph taken at age 18–25 with another taken 10, 20 or 30 years later.

Aging can affect:

• Skin
• Cheeks
• Jaw definition
• Facial fat
• Eyelids
• Hairline
• Hair density
• Facial width appearance

NIST notes that aging changes appearance over decades and can eventually make automated recognition more difficult.

Therefore, greater weight should generally be placed on adequately visible structural relationships than on temporary appearance.

19. Separate Relatively Stable Features From Changeable Features

A practical comparison can divide observations into two broad groups.

More structurally informative characteristics

Depending on image quality, these may include:

• General facial proportions
• Eye spacing
• Nose morphology
• Ear morphology
• Relative feature positions
• Chin structure
• Persistent asymmetry

Highly changeable characteristics

These include:

• Hairstyle
• Hair length
• Beard
• Moustache
• Skin appearance
• Makeup
• Body weight
• Cheek fullness
• Facial expression
• Clothing
• Eyeglasses

Do not give hairstyle the same importance as anatomical morphology.

20. Camera Perspective Can Create False Differences

Suppose Photo A was taken from approximately two metres away while Photo B was taken very close to the face.

Perspective can alter the apparent relationships among facial features.

Similarly, different lenses and cropping can change the apparent proportions.

This is why photograph comparison should not rely on a single measurement unless acquisition conditions and geometric assumptions justify it.

21. Lighting Can Change Perceived Facial Structure

Lighting from above may create:

• Deep eye shadows
• Narrow-looking cheeks
• Strong jaw definition

Lighting directly from the front can flatten facial contours.

Side lighting can make one half of the face appear narrower or wider.

Therefore:

shadow is not anatomy.

22. Image Enhancement Has Limits

Brightness, contrast, sharpening and enlargement may make an existing feature easier to see.

However, enhancement cannot reliably reconstruct facial details that were never captured.

For example, enlarging a 20-pixel-wide face to 1,000 pixels does not magically produce genuine anatomical detail.

AI enhancement is particularly important to treat cautiously because generated detail may look realistic without necessarily representing the original subject accurately.

For comparison purposes, always preserve the original image.

23. A Practical Comparison Table

A useful worksheet can look like this:

Feature	Photo A	Photo B	Assessment
Face proportions	Long/narrow	Long/narrow	Similar
Forehead	Broad	Broad	Similar
Hairline	Visible	Visible	Some similarity
Eyebrows	Thick/straight	Thick/straight	Similar
Eye shape	Oval	Oval	Similar
Eye spacing	Moderate	Moderate	Similar
Nose bridge	Straight	Straight	Similar
Nose tip	Rounded	Rounded	Some similarity
Upper lip	Thin	Thin	Similar
Lower lip	Fuller	Fuller	Similar
Chin	Narrow	Broader	Some difference
Jaw	Narrow	Wider	Different appearance
Ears	Projecting	Projecting	Similar general appearance
Scar/mark	Not visible	Not visible	Cannot assess

Use terms such as:

Similar
Somewhat similar
Different appearance
Cannot reliably assess

This avoids unjustified certainty.

24. Avoid Assigning Arbitrary Match Percentages

Statements such as:

"These photographs are a 92% match"

should not be produced simply by counting similar-looking features.

For example, if 9 of 10 manually selected characteristics appear similar, that does not scientifically establish a 90% probability that the subjects are the same individual.

Different facial characteristics do not necessarily carry equal evidential weight, and some observations are correlated.

25. Human Comparison vs Facial Recognition Software

These are different processes.

Human morphological comparison

A person visually evaluates individual facial components and documents similarities and differences.

Automated facial recognition

Software extracts computational representations from facial images and calculates similarity according to an algorithm.

NIST evaluates face-recognition algorithms and reports both false-positive and false-negative behavior. Performance varies with the algorithm, application and image conditions.

A software similarity score should therefore not automatically be interpreted as a literal probability that two people are identical.

26. False Positives and False Negatives

Two important concepts are:

False Positive

Two different people are incorrectly associated.

False Negative

Two photographs of the same person fail to associate.

NIST notes that false negatives are strongly dependent on image quality and identifies poor illumination and pose-related differences as examples that can increase errors.

This illustrates why visual resemblance alone is insufficient for high-stakes identification.

27. Recommended Step-by-Step Workflow

For an ordinary visual comparison, use this workflow:

Step 1: Obtain the highest-quality originals available.

Step 2: Prefer photographs with similar head orientation.

Step 3: Record approximate dates or ages if known.

Step 4: Evaluate resolution, focus and lighting.

Step 5: Examine overall facial proportions.

Step 6: Compare forehead and hairline.

Step 7: Compare eyebrows independently.

Step 8: Compare eyes and eye spacing.

Step 9: Examine nose bridge, tip and base.

Step 10: Compare mouth and lip relationships.

Step 11: Compare chin and jaw.

Step 12: Examine ears if adequately visible.

Step 13: Record scars, marks or persistent asymmetries.

Step 14: Consider aging, weight and hairstyle.

Step 15: Record differences as carefully as similarities.

Step 16: Mark unclear characteristics as "cannot assess."

Step 17: Avoid converting observations into an unsupported identity percentage.

Step 18: For legal, forensic or other consequential decisions, use a qualified professional and corroborating evidence.

28. Why Multiple Photographs Are Better

When possible, obtain several photographs from each time period.

For example:

Earlier period

• Frontal photograph
• Slight left-facing photograph
• Slight right-facing photograph

Later period

• Frontal photograph
• Slight left-facing photograph
• Slight right-facing photograph

Multiple images help distinguish genuine characteristics from temporary effects caused by expression, lighting or pose.

29. What Should Not Be Used as Primary Evidence?

Avoid relying primarily on:

• Hairstyle
• Clothing
• Background
• Skin brightness
• Apparent complexion caused by lighting
• Smile
• Beard
• Moustache
• Eyeglasses
• Photograph colour
• Image sharpness

These characteristics may change or may result from photographic conditions rather than anatomy.

30. Documentation Is Important

Professional guidance emphasizes documenting morphological analysis, with more rigorous documentation expected in forensic examination.

For an informal comparison, preserve:

• Original Photo A
• Original Photo B
• Approximate photograph dates if known
• Unedited copies
• Notes about image quality
• Feature comparison table
• Observed similarities
• Observed differences
• Features that could not be assessed

This is much better than relying on memory.

31. A Simple Scoring System for Organization — Not Identification

For personal organization, you could label observations:

S — Similar
PS — Partially Similar
D — Different Appearance
NA — Not Assessable

For example:

Feature	Result
Face proportions	S
Eyebrows	S
Eyes	PS
Nose	S
Mouth	S
Chin	PS
Jaw	D
Ears	PS
Hairline	NA

However, do not add these labels together to produce an identity probability.

The table is simply a structured record of observations.

32. Special Case: Comparing an Old ID Photograph With a Recent Photograph

This is common with:

• Old passports
• Driving licences
• Employee ID cards
• School records
• Tax documents
• Membership cards
• Historical records

An old ID photograph may have:

• Low resolution
• Printing artifacts
• Scanning distortion
• Colour shifts
• Compression
• Blur

In such situations, compare only features that are genuinely visible.

If nostrils cannot be resolved, record:

Nostrils — cannot assess

rather than guessing.

33. Can AI Determine Whether Two Old and New Photographs Show the Same Person?

AI systems can analyze facial images, but their outputs must be interpreted carefully.

Accuracy can be influenced by:

• Image quality
• Age difference
• Pose
• Illumination
• Resolution
• Occlusion
• Algorithm design
• Population characteristics

NIST's ongoing Face Recognition Technology Evaluation demonstrates that algorithm performance and error characteristics vary, including with image quality and demographic factors.

Therefore, AI output should not automatically be treated as definitive identity evidence.

34. Best-Practice Principle

A useful principle is:

Compare individual observable characteristics, document both similarities and differences, account for image conditions and aging, and avoid turning visual resemblance into unsupported certainty.

Modern forensic guidance supports systematic morphological examination rather than casual overall resemblance judgments. ASTM's facial-image comparison feature-list standard provides a framework for consistent terminology and examination of facial components and characteristics.

Frequently Asked Questions (FAQ)

1. Can two photographs taken 20 years apart still be compared?

Yes. Visible facial characteristics can be compared, but aging and image conditions must be considered.

2. Which facial features should I compare?

Consider overall facial proportions, eyebrows, eyes, nose, mouth, lips, chin, jaw, ears, hairline and visible distinctive characteristics.

3. Which feature is the most important?

There is no single universally decisive visible feature. A systematic assessment considers multiple adequately visible characteristics.

4. Are ears useful when comparing photographs?

They can provide useful morphological characteristics when both ears are clearly visible at suitable resolution and angle.

5. Is the nose useful?

Yes. Bridge, tip, base, nostrils and relative proportions can be examined when image quality permits.

6. Can hairstyle be used?

It can be documented, but hairstyle is easily changed and should not carry much weight.

7. Can aging change the jawline?

Yes. Aging, weight and soft-tissue changes can substantially alter its appearance.

8. Can weight gain make two photographs appear different?

Yes. It can affect cheeks, jawline, neck and overall apparent facial width.

9. Can lighting change nose appearance?

Yes. Shadows and highlights can significantly change perceived shape.

10. Can camera angle change facial proportions?

Yes. Perspective and head orientation can alter apparent dimensions and feature relationships.

11. Should I compare pixel measurements?

Raw pixel measurements from differently scaled or perspectively different photographs should not be treated as directly equivalent. Relative proportions can sometimes be more informative, provided limitations are understood.

12. Can an enlarged low-resolution photograph become reliable?

Enlargement may make existing information easier to view, but it cannot recreate genuine detail that was never captured.

13. Should AI-enhanced photos be used for comparison?

Prefer originals. AI enhancement can introduce generated details, so enhanced images should not replace source images for serious comparison.

14. Are scars and moles useful?

Potentially, provided they are clearly visible in both photographs and are not confused with compression artifacts, shadows or temporary skin features.

15. Is eye colour enough to match two photographs?

No.

16. Is facial similarity proof that two photographs depict the same person?

No. Different people can have similar facial characteristics.

17. Can I calculate a percentage match manually?

A simple percentage created by counting visually similar features is not a scientifically justified identity probability.

18. What is morphological facial analysis?

It is a systematic method of comparing facial components and their characteristics, such as shape, appearance, symmetry, location and relative proportion.

19. Should similarities and differences both be recorded?

Yes. Recording only similarities introduces confirmation bias.

20. What should I write when a feature is unclear?

Use "cannot reliably assess" rather than guessing.

21. What photographs are best for comparison?

Clear, well-focused, well-lit photographs with frontal or closely comparable head orientations are preferable.

22. Are passport-style photographs useful?

Generally, a clear frontal passport-style photograph can provide good visible facial information because pose and background are relatively controlled.

23. Can old scanned photographs be compared?

Yes, but scanning, printing, compression and deterioration must be considered.

24. Can facial expression affect comparison?

Yes. Smiling, frowning and other expressions can alter eyes, cheeks, lips and jaw appearance.

25. Can facial comparison be used as legal proof?

Informal visual comparison should not be treated as legal or forensic identification. High-stakes cases require appropriately qualified practitioners, validated procedures and supporting evidence.

Conclusion

Comparing photographs taken at different ages is much more complicated than simply deciding whether two faces "look alike."

A systematic approach examines:

overall proportions → forehead → eyebrows → eyes → nose → cheeks → mouth → lips → chin → jaw → ears → distinctive characteristics

while simultaneously considering:

age → weight → expression → lighting → pose → resolution → perspective → image processing.

The strongest approach is not to search only for similarities. Instead, document similarities, differences and characteristics that cannot reliably be evaluated.

Professional facial comparison uses structured methodologies and standardized terminology, and image quality plays a fundamental role in determining what can actually be compared.

For ordinary personal or historical-photo research, a feature-by-feature worksheet can make comparisons much more systematic. But where identity has legal, financial, employment, immigration, criminal-investigative or other serious consequences, visual comparison alone should not be considered sufficient.

Disclaimer: This article is provided for general educational and informational purposes. It is not a forensic identification procedure, biometric certification, legal opinion or proof of identity. Facial resemblance does not establish that two photographs depict the same person. For legal, investigative or other consequential identification, consult appropriately qualified professionals and use suitable corroborating evidence.