Contrast
Contrast comparison
Image Contrast Comparison
Adjust contrast and compare tonal separation between shadows, midtones, and highlights.
- Browser-local processing
- PNG · JPG · WebP
- No account needed
Original vs current edit
Compare the original image with the current adjustment state.
Upload an image to compare contrast changes with the original.
Tonal range
Luma contrast
Clipping risk
Advanced metrics
Upload an image to calculate luma, clipping, contrast, and chroma metrics.
Luma histogram
Histogram appears after an image is uploaded.
Original Current edit
Image session actions
Upload an image to compare contrast changes with the original.
How to read this page
Contrast changes tonal separation
Contrast comparison focuses on tonal separation. Higher contrast usually increases the distance between darker and brighter tones, while lower contrast can flatten the image. Use tonal range and clipping metrics to catch harsh edits.
Scope
Contrast can make an image look sharper, but it can also remove usable shadow or highlight detail.
Contrast comparison guide
What Contrast Comparison Shows
Compare photo contrast
The image contrast comparison viewer shows how dark and bright areas separate after a contrast before after adjustment.
Read tonal range and RMS contrast
Tonal range, luma contrast, and shadow highlight separation help identify low contrast images and overly hard edits.
Contrast vs levels
Contrast broadly changes tonal separation. Levels directly controls black point, white point, midtones, output range, and curve response.
Contrast terms and calculations
How to Read an Image Contrast Comparison
Image contrast comparison is about separation. A photo contrast comparison should tell you whether shadows, midtones, and highlights gained useful distance from each other or whether the edit simply became harsh. Contrast before after review is different from brightness review because brightness moves values lighter or darker, while contrast changes the spacing between values. This is why a low contrast image can still be bright, and a high contrast photo can still be too dark.
A common contrast concept expands values around a pivot, often 0.5 in normalized display space: output = (input - pivot) * factor + pivot. When factor is greater than 1, dark values move darker and bright values move brighter. When factor is less than 1, values compress toward the pivot. Image contrast comparison should therefore inspect tonal range, luma standard deviation, RMS contrast, shadow highlight separation, and clipping risk. The goal is not maximum contrast; the goal is enough separation for the subject, texture, and depth to remain clear.
Use image contrast comparison when the photo looks flat, muddy, brittle, or too punchy. A useful image contrast comparison checks local detail as well as global tonal range, because the same image contrast comparison can show better subject shape while also revealing crushed shadows or clipped highlights.
Tonal range
Tonal range describes the distance between dark and bright percentiles, often P95 minus P5.
- Role in the image
- In an image contrast comparison, tonal range shows whether the edit expanded or compressed useful tones.
- Concept or calculation
- P95 - P5 avoids being dominated by a few extreme pixels while still describing broad separation.
- Watch for
- A larger tonal range can look stronger, but it can also hide texture in deep shadows or bright highlights.
RMS contrast
RMS contrast is related to variation around average luma.
- Role in the image
- Photo contrast comparison uses RMS contrast to describe how much luma values vary across the image.
- Concept or calculation
- A simple RMS idea is the square root of the average squared difference from mean luma.
- Watch for
- Texture-heavy images can produce high RMS contrast even when the subject lacks good global separation.
Luma standard deviation
Luma standard deviation measures how spread out brightness values are around their average.
- Role in the image
- It helps explain whether the current edit has more or less tonal variety than the original.
- Concept or calculation
- Standard deviation rises when many pixels move away from the mean and falls when values cluster together.
- Watch for
- Noise and grain can increase this number without making the image visually better.
Shadow highlight separation
Shadow highlight separation describes the distance between dark percentile values and bright percentile values.
- Role in the image
- In contrast before after review, this shows whether the edit created stronger depth.
- Concept or calculation
- Compare P5, P50, and P95 together to see whether shadows, midtones, and highlights all moved or only the endpoints changed.
- Watch for
- If endpoints move but midtones do not, the image can look punchy but unnatural.
Clipping risk
Clipping risk measures whether contrast pushed dark or bright pixels into hard limits.
- Role in the image
- Image contrast comparison uses clipping risk to warn when stronger contrast damages detail.
- Concept or calculation
- In 8-bit terms, values near 0 or 255 represent the areas most likely to lose separation.
- Watch for
- Check black clothing, hair, white objects, skies, and bright reflections after increasing contrast.
Contrast with brightness
Use brightness to set the general lightness, then use image contrast comparison to check separation. If you only increase brightness, the photo may become flat. If you only increase contrast, the photo may become dramatic but too hard.
Contrast with levels
Contrast comparison is broad. Levels comparison is precise. If contrast before after metrics show endpoint damage, move to levels to control black point, white point, and midtones directly.
FAQ
About this page
Why use side-by-side for contrast?
Side-by-side comparison makes tonal separation easier to scan across the whole image.
Does contrast sharpen the image?
It can make edges feel stronger, but this tool is changing tonal contrast, not running a sharpening filter.
How is contrast different from brightness?
Brightness shifts values lighter or darker. Contrast changes the distance between dark and bright tones.