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Contrast effect

  • Стаття

Increases or decreases the contrast of an image.

The CLSID for this effect is CLSID_D2D1Contrast.

The contrast function modifies each color channel value using two, piecewise quadratic polynomials that meet with slope continuity at the point (0.5, 0.5).

piecewise quadratic polynomials that meet with slope continuity at the point (0.5, 0.5)

Example images

This example shows the output of the effect with maximum contrast applied (Contrast = 1.0).

Before

image before effect is applied

After

image after effect is applied

Sample code

ComPtr<ID2D1Effect> contrastEffect;
m_d2dContext->CreateEffect(CLSID_D2D1Contrast, &contrastEffect);
 
contrastEffect->SetInput(0, bitmap);
contrastEffect->SetValue(D2D1_CONTRAST_PROP_CONTRAST, 0.5f);
contrastEffect->SetValue(D2D1_CONTRAST_PROP_CLAMP_INPUT, TRUE);
 
m_d2dContext->BeginDraw();
m_d2dContext->DrawImage(contrastEffect.Get());
m_d2dContext->EndDraw();

Effect properties

The properties for the contrast effect are defined by the D2D1_CONTRAST_PROP enumeration.

Requirements

Requirement Value
Minimum supported client Windows 10 [desktop apps | Windows Store apps]
Minimum supported server Windows 10 [desktop apps | Windows Store apps]
Header d2d1effects_2.h
Library d2d1.lib, dxguid.lib