Levels and Curves: fix brightness and contrast
Brightness and contrast sliders are blunt: they move every tone by the same amount. Levels and Curves let you decide which tones change and by how much. They are the two tools photographers reach for first when a picture looks flat, dark or washed out.
Levels: set the black point, white point and midtones
Levels shows a histogram — how many pixels there are at each brightness, from black on the left to white on the right. A dull photo often has a histogram that doesn't reach either end.
- Move Input black to where the histogram starts: those pixels become pure black.
- Move Input white to where it ends: those become pure white. The tones in between stretch to fill the full range, and contrast improves.
- Gamma brightens or darkens the midtones without moving black and white.
- Output black and white do the opposite — they compress the range, for a faded, matte look.
Curves: control every tone
Curves draws a line from dark (bottom left) to light (top right). Bending it changes tones: lift a point and those tones get brighter, lower it and they get darker.
- S-curve: lower a point in the shadows and raise one in the highlights for punchier contrast.
- Lift the bottom-left end for faded blacks.
- One channel at a time: switch to Red, Green or Blue to remove a colour cast — for example, lower the blue curve slightly to warm up a cold photo.
Why adjustment layers
In Picstea, Levels and Curves are adjustment layers. They change how the image looks, not its pixels: hide the layer to compare, change the settings later, or paint on its mask to apply the correction to only part of the image.
Try it
- Open a photo in Picstea.
- Choose Adjustments → Levels and drag the black and white inputs to the ends of the histogram.
- Add Adjustments → Curves above it and make a gentle S-curve.
- Toggle the layers' eye icons to compare before and after.
Everything happens in your browser — the photo is never uploaded. Read more in the layers documentation.