greycardThe histogram and the scopes
The scopes sit at the top of the right panel, under the file's name, and stay there while the sections scroll. They are hidden while you cull. Pick one from the row under it:
| Scope | Shows |
|---|---|
| RGB | the histogram: how many pixels at each level, dark at the left, bright at the right |
| Wave | a waveform: brightness up the scope against the picture's columns across it, so you can see where in the frame the bright and dark parts are |
| Parade | the same as Wave, with red, green and blue side by side |
| Vector | the colors on a wheel: grey in the middle, stronger color further out, with a line where skin tones fall |
The scope you pick is remembered. The histogram also shows behind the curve in CURVES, on the Develop tab and in a mask.
Point at the picture and the scope shows that spot. Its levels, 0 to 255, appear at the top of the scope: R, G and B, and L for its brightness. On RGB a line runs through each one; on Wave and Parade a dot per channel sits at the spot's place across the frame; on Vector a ring shows where its color falls, so you can rest the pointer on a cheek and see it against the skin line. The readout is of a small area around the pointer as the scopes see it, not of one pixel at 1:1.
With Selection on, a spot outside the mask is not counted on the scope, so its marks show faded and its numbers dimmed: rest the pointer on the background with a skin mask chosen to see where it falls against the skin.
The scopes read the picture as it will be written, in the color space set in the export sheet, not the camera's raw data. For Adobe RGB they read the value on the sRGB curve, not the file's own gamma, so the clipping ends are the same and the shadows read differently.
Reading one mask: Selection
Selection, beside the scope choices, makes every scope count only the pixels in the chosen mask. On a skin mask, Vector shows the skin alone against the skin line; on a face mask, Wave shows the face's level without the background over it.
It works on the Masks tab with a mask chosen that has a shape, and is greyed otherwise. It is off each time greycard starts. While it is on, the clipping lamps on the histogram follow the mask too. See Masks.
Clipping
On the RGB histogram, two small squares at the top corners light when part of the picture is pure black (left) or pure white (right). Their color says which channels clip: red, green or blue for one, yellow, magenta or cyan for two, white for all three.
Click a square to paint that end's clipping over the picture: blue where it is black, red where it is white. Press J to turn both on, or both off. The choice is remembered.
The lamps say what the exported file will clip after the tone curve, not what the camera's sensor clipped. The painted warning always covers the whole frame, even with Selection on.
Focus peaking
Press Shift+J in the Loupe, in Cull or Develop, to paint the sharpest parts of the picture green, and again to take the paint off. The measure is the picture's own, so a frame sharp in one place paints there and a frame sharp throughout paints most of itself. It is taken on the picture as shown, so at 1:1 it finds a missed focus that Fit hides. The choice is remembered.
Soft proofing
A soft proof shows how the picture will look in a narrower color space, or on a printer, before you export. Press S, or use the switch on SOFT PROOF at the end of the Develop tab.
- sRGB, Display P3, Rec.2020, Adobe RGB or File: the space to proof against. File takes an ICC profile, such as a printer's, through Choose....
- Perceptual or Relative: how colors outside the profile are brought in. For sRGB, Display P3, Rec.2020 and Adobe RGB the two look the same; the choice matters for a printer profile.
- Gamut warning paints grey where a color falls outside the profile. It is off until you switch it on.
The profile and the intent are remembered; whether the proof is on is not.
While the proof is on, a small badge in the top left corner of the picture names it, as in "Proof: sRGB", with "· gamut" added when the gamut warning is on. Click the badge, or press S again, to turn the proof off. Culling never shows the badge: the camera's JPEG is not proofed.
Your monitor's profile
The MONITOR section, after SOFT PROOF, sets the profile greycard uses to show colors on your screen. A line under it says what the profile changes.
| Choice | Use it when |
|---|---|
| System | on Linux and macOS, to use the profile your desktop has for the monitor; with several monitors, pick yours below |
| sRGB | your monitor is an ordinary sRGB screen |
| Adobe RGB, Display P3 | your monitor is set to emulate that space in its own menu |
| File | you have an ICC profile for the monitor, from a calibrator or its maker; pick it with Choose... |
On Windows, greycard cannot read the system's monitor profile yet,
so System shows colors as sRGB. On a wide-gamut screen colors
then look too saturated. Pick the monitor's ICC profile with File
(Windows keeps them in C:\Windows\System32\spool\drivers\color),
or one of the named spaces if the monitor is set to it.
Canvas sets the color around the picture: black, one of three greys, or white. F gives the fitted picture a mat of it on every side.
The monitor choice is remembered. It changes only what you see; an export is never affected.
How greycard handles light
You don't need this to edit, but it explains why the sliders behave as they do.
greycard works on the light the camera recorded, not on screen brightness. Every slider acts on that light, and only at the very end does a display curve fit it to the screen. So:
- Exposure is a true stop: +1 doubles the light, in the shadows and the highlights alike.
- Bright parts keep their detail through the edit; they are rolled off gently by the display curve, not cut off at white early.
- Colors stay wide until the end, so a strong color edit doesn't hit a wall partway through.
The display curve is either Per channel (the default) or AgX; the switch is at the foot of LIGHT. See Develop.
For the technically minded: the working space is linear Rec.2020.