Adjust Brightness & Contrast
Adjust brightness, contrast, and saturation of your photos for free, right in your browser.
.jpg, .png, .webp · up to 50 MB
Why use it
Professional color correction, no software needed
Compatible everywhere
JPG, PNG, and WebP. The result works on any platform.
100% private
Processing happens in your browser. Your image never leaves your device.
Correct HSL model
Perceptual adjustments based on the HSL model, not crude linear manipulation.
Instant
Real-time preview. No queues, no signup, no limits.
How it works
Three steps, no hassle
Upload your image
Drag and drop or select a JPG, PNG, or WebP. Up to 50 MB. No signup.
Adjust the controls
Move the brightness, contrast, and saturation sliders. The preview updates in real time.
Download the result
Processed in your browser. No watermark, no additional quality loss.
FAQ
Got questions?
Brightness is a linear adjustment that adds or subtracts the same value uniformly to every pixel. Adding +30 brightness means each R, G, and B channel receives exactly +30, which lightens the image but also blows out highlights. Exposure, in contrast, is a multiplicative adjustment that respects the tonal relationship between pixels: increasing by 1 EV (Exposure Value) doubles each pixel's value (×2), mimicking how a camera receives twice as much light. Exposure adjustments produce more natural results because they better preserve contrast in shadows and highlights. For professional photographic correction, exposure adjustments are always preferable to linear brightness.
The Web Content Accessibility Guidelines (WCAG 2.1) define color contrast requirements to ensure text is readable for people with low vision or color blindness. Level AA requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text (≥18pt or ≥14pt bold). Level AAA requires 7:1 and 4.5:1 respectively. The formula uses relative luminance: (L1 + 0.05) / (L2 + 0.05), where L is luminance calculated using perceptual weights (0.2126R + 0.7152G + 0.0722B). Tools like TPGi's Colour Contrast Analyser automatically calculate whether a color combination meets WCAG.
The most common cause is display miscalibration: desktop monitors and phones have different color profiles (sRGB, P3, AMOLED) with different brightness levels, gamma, and color gamut. AMOLED phones typically have extremely high contrast and deep blacks, making images with lots of shadows appear nearly black. A second cause is incorrect color management: if an image was created with a P3 color profile (wider gamut) and displayed on a system that interprets the data as sRGB, colors appear darker and more muted. The professional solution is to calibrate your monitor with a colorimeter and export images with an embedded sRGB profile for maximum compatibility.
An underexposed photo has most of its tonal information compressed in the shadows of the histogram. The most effective correction is not simply increasing brightness, but a combination of: (1) Increasing exposure or shadows to recover detail in dark areas. (2) Applying a gentle S-curve to add contrast simultaneously. (3) Adjusting levels (input levels) by moving the white point left to where the real histogram data begins. (4) Slightly increasing clarity to recover microcontrast in details. If the underexposure is extreme (more than 3 stops), digital noise in the recovered shadows can be unacceptable, especially in photos taken at high ISO values.
Saturation increases the intensity of all colors uniformly — it pushes every color toward its purest, most intense version regardless of how saturated it already is. Applied excessively, skin tones and already-saturated colors become plastic and unnatural. Vibrance (called 'Intensidad' in Adobe Lightroom's Spanish interface) is a smart version of saturation: it applies the increase preferentially to less saturated colors while protecting skin tones and those already near maximum saturation. The result is a boost in colorfulness that looks natural. For people photography, always use vibrance instead of saturation; for nature or product photography, both can work well.
Color correction: HSL model, gamma correction, and visual perception
Adjusting brightness and contrast seems simple but involves decades of visual perception science. The human eye does not perceive light linearly — it roughly follows the Weber-Fechner Law: the perception of a stimulus difference is proportional to the baseline level of that stimulus. This means we perceive the difference between 10 and 20 candelas as greater than between 100 and 110 candelas, even though the absolute difference is the same. This non-linear characteristic is why monitors apply gamma correction: the relationship between the digital value (0–255) and emitted light follows a power curve (V_out = V_in^gamma) with gamma ≈ 2.2 for sRGB.
The HSL (Hue, Saturation, Lightness) color model was developed by Alvy Ray Smith in 1978 at Xerox PARC to provide a more intuitive color representation for humans. Unlike RGB, which mixes primary light components, HSL separates color into three independent properties that correspond to how we describe color naturally: hue (what color it is), saturation (how intense it is), and lightness (how light or dark it is). This enables independent adjustments with more predictable results: increasing lightness in HSL does not affect hue or saturation, whereas increasing the blue channel in RGB simultaneously changes the color balance, perceived saturation, and brightness.
Web accessibility contrast requirements have direct implications for interface design. WCAG 2.1 (Web Content Accessibility Guidelines), developed by the W3C, establishes that approximately 300 million people worldwide have some form of color blindness, and more than 2.2 billion have some type of visual impairment. The minimum contrast ratio of 4.5:1 for text ensures readability for people with reduced vision to 20/80 (with glasses). Designing with adequate contrast is not just about accessibility — high-contrast interfaces improve readability for all users, especially under direct sunlight on mobile devices.