Color Conversion - Android

import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import ly.img.engine.CMYKColor
import ly.img.engine.Color
import ly.img.engine.ColorSpace
import ly.img.engine.Engine
import ly.img.engine.RGBAColor
import ly.img.engine.SpotColor

suspend fun colorConversion(engine: Engine): ColorConversionResult = withContext(Dispatchers.Main) {
    // Define a spot color with an RGB approximation for screen preview.
    engine.editor.setSpotColor(
        name = "Brand Red",
        color = Color.fromRGBA(r = 0.95F, g = 0.25F, b = 0.21F, a = 1F),
    )

    val srgbColor = Color.fromRGBA(r = 0.2F, g = 0.4F, b = 0.9F, a = 1F)
    val cmykColor = Color.fromCMYK(c = 0F, m = 0.8F, y = 0.95F, k = 0F, tint = 1F)
    val spotColor = Color.fromSpotColor(
        name = "Brand Red",
        tint = 1F,
        externalReference = "",
    )

    // A CMYK conversion reads the document CMYK profile, which is a resource. Load it once so the
    // conversions below do not have to handle COLOR.PROFILE_NOT_LOADED.
    engine.editor.loadCMYKProfile()

    val cmykToSrgb = engine.editor.convertColorToColorSpace(
        color = cmykColor,
        colorSpace = ColorSpace.SRGB,
    ) as RGBAColor

    val spotToSrgb = engine.editor.convertColorToColorSpace(
        color = spotColor,
        colorSpace = ColorSpace.SRGB,
    ) as RGBAColor

    println("CMYK converted to sRGB: $cmykToSrgb")
    println("Spot color converted to sRGB: $spotToSrgb")

    val srgbToCmyk = engine.editor.convertColorToColorSpace(
        color = srgbColor,
        colorSpace = ColorSpace.CMYK,
    ) as CMYKColor

    // Add a CMYK approximation before converting the spot color for print output.
    engine.editor.setSpotColor(
        name = "Brand Red",
        color = Color.fromCMYK(c = 0F, m = 0.85F, y = 0.9F, k = 0.05F, tint = 1F),
    )
    val spotToCmyk = engine.editor.convertColorToColorSpace(
        color = spotColor,
        colorSpace = ColorSpace.CMYK,
    ) as CMYKColor

    println("sRGB converted to CMYK: $srgbToCmyk")
    println("Spot color converted to CMYK: $spotToCmyk")

    val detectedTypes = listOf(srgbColor, cmykColor, spotColor).map { color ->
        when (color) {
            is RGBAColor -> "sRGB"
            is CMYKColor -> "CMYK"
            is SpotColor -> "SpotColor"
        }
    }

    val transparentSrgb = Color.fromRGBA(r = 0.2F, g = 0.4F, b = 0.9F, a = 0.5F)
    val transparentSrgbToCmyk = engine.editor.convertColorToColorSpace(
        color = transparentSrgb,
        colorSpace = ColorSpace.CMYK,
    ) as CMYKColor

    val tintedCmyk = Color.fromCMYK(c = 0F, m = 0.8F, y = 0.95F, k = 0F, tint = 0.5F)
    val tintedCmykPreview = engine.editor.convertColorToColorSpace(
        color = tintedCmyk,
        colorSpace = ColorSpace.SRGB,
    ) as RGBAColor

    val tintedSpotColor = Color.fromSpotColor(
        name = "Brand Red",
        tint = 0.4F,
        externalReference = "",
    )
    val tintedSpotPreview = engine.editor.convertColorToColorSpace(
        color = tintedSpotColor,
        colorSpace = ColorSpace.SRGB,
    ) as RGBAColor
    val tintedSpotToCmyk = engine.editor.convertColorToColorSpace(
        color = tintedSpotColor,
        colorSpace = ColorSpace.CMYK,
    ) as CMYKColor

    val colorFromDesign: Color = spotColor
    val pickerPreviewColor = engine.editor.convertColorToColorSpace(
        color = colorFromDesign,
        colorSpace = ColorSpace.SRGB,
    ) as RGBAColor
    // Display pickerPreviewColor.r, pickerPreviewColor.g, pickerPreviewColor.b, and pickerPreviewColor.a.

    val colorForExport: Color = srgbColor
    val printColor = if (colorForExport is CMYKColor) {
        colorForExport
    } else {
        engine.editor.convertColorToColorSpace(
            color = colorForExport,
            colorSpace = ColorSpace.CMYK,
        ) as CMYKColor
    }

    ColorConversionResult(
        cmykToSrgb = cmykToSrgb,
        spotToSrgb = spotToSrgb,
        srgbToCmyk = srgbToCmyk,
        spotToCmyk = spotToCmyk,
        transparentSrgbToCmyk = transparentSrgbToCmyk,
        tintedCmykPreview = tintedCmykPreview,
        tintedSpotPreview = tintedSpotPreview,
        tintedSpotToCmyk = tintedSpotToCmyk,
        detectedTypes = detectedTypes,
        pickerPreviewColor = pickerPreviewColor,
        printColor = printColor,
    )
}

import ly.img.engine.CMYKColor
import ly.img.engine.RGBAColor

data class ColorConversionResult(
    val cmykToSrgb: RGBAColor,
    val spotToSrgb: RGBAColor,
    val srgbToCmyk: CMYKColor,
    val spotToCmyk: CMYKColor,
    val transparentSrgbToCmyk: CMYKColor,
    val tintedCmykPreview: RGBAColor,
    val tintedSpotPreview: RGBAColor,
    val tintedSpotToCmyk: CMYKColor,
    val detectedTypes: List<String>,
    val pickerPreviewColor: RGBAColor,
    val printColor: CMYKColor,
)

Convert colors between sRGB, CMYK, and spot color spaces programmatically in CE.SDK.

7 mins

estimated time

GitHub

CE.SDK supports sRGB, CMYK, and SpotColor values. Color conversion is a programmatic Engine API on Android, so use it when you build custom color interfaces, show print values, or prepare colors before export.

This guide covers converting colors to sRGB and CMYK, converting spot colors through their approximations, identifying Android color types, and checking how alpha and tint values are preserved.

Supported Color Spaces#

CE.SDK works with these Android color value types:

Color Space	Android Type	Use Case
sRGB	`RGBAColor` with `r`, `g`, `b`, `a` components from `0.0` to `1.0`	Screen display and previews
CMYK	`CMYKColor` with `c`, `m`, `y`, `k`, `tint` components from `0.0` to `1.0`	Print workflows
SpotColor	`SpotColor` with `name`, `tint`, and `externalReference`	Specialized printing with named inks

Use ColorSpace.SRGB or ColorSpace.CMYK as conversion targets. A SpotColor can be converted by using the RGB or CMYK approximation registered for its name.

Setting Up Colors#

Before converting a spot color, register an approximation for the spot color name. Android uses the overloaded setSpotColor(...) API for both RGB and CMYK approximations.

// Define a spot color with an RGB approximation for screen preview.
engine.editor.setSpotColor(
    name = "Brand Red",
    color = Color.fromRGBA(r = 0.95F, g = 0.25F, b = 0.21F, a = 1F),
)

Create color values with the Android Color factory methods. The sample uses the same sRGB, CMYK, and spot color values throughout the conversion steps.

val srgbColor = Color.fromRGBA(r = 0.2F, g = 0.4F, b = 0.9F, a = 1F)
val cmykColor = Color.fromCMYK(c = 0F, m = 0.8F, y = 0.95F, k = 0F, tint = 1F)
val spotColor = Color.fromSpotColor(
    name = "Brand Red",
    tint = 1F,
    externalReference = "",
)

Loading the CMYK Profile#

In Managed scenes, RGB-to-CMYK conversion uses the document CMYK profile, or the fallback profile when no document profile is available. The synchronous conversion reports COLOR.PROFILE_NOT_LOADED only while a profile from a URI loads.

Await loadCMYKProfile() before converting colors to avoid this loading error:

engine.editor.loadCMYKProfile()

The loading call can fail if no usable profile is available. RGB-to-CMYK conversion uses a simple formula if the profile cannot load or only converts CMYK to RGB. Legacy scenes always use the simple formula for RGB-to-CMYK conversion.

Converting to sRGB#

Use engine.editor.convertColorToColorSpace(color, ColorSpace.SRGB) when you need screen-display values. The returned value is a Color, so cast it to RGBAColor after converting to sRGB.

val cmykToSrgb = engine.editor.convertColorToColorSpace(
    color = cmykColor,
    colorSpace = ColorSpace.SRGB,
) as RGBAColor

val spotToSrgb = engine.editor.convertColorToColorSpace(
    color = spotColor,
    colorSpace = ColorSpace.SRGB,
) as RGBAColor

println("CMYK converted to sRGB: $cmykToSrgb")
println("Spot color converted to sRGB: $spotToSrgb")

CMYK colors convert to RGBAColor components. Spot colors use the registered RGB approximation for their spot color name. When the source color has a tint below 1.0, the returned sRGB color keeps a = 1.0 and blends its RGB components toward white.

Converting to CMYK#

Use engine.editor.convertColorToColorSpace(color, ColorSpace.CMYK) when a print workflow needs CMYK components. Spot colors retain a registered CMYK approximation. In Managed scenes, a spot with only an RGB approximation converts through the CMYK profile with its tint applied.

val srgbToCmyk = engine.editor.convertColorToColorSpace(
    color = srgbColor,
    colorSpace = ColorSpace.CMYK,
) as CMYKColor

// Add a CMYK approximation before converting the spot color for print output.
engine.editor.setSpotColor(
    name = "Brand Red",
    color = Color.fromCMYK(c = 0F, m = 0.85F, y = 0.9F, k = 0.05F, tint = 1F),
)
val spotToCmyk = engine.editor.convertColorToColorSpace(
    color = spotColor,
    colorSpace = ColorSpace.CMYK,
) as CMYKColor

println("sRGB converted to CMYK: $srgbToCmyk")
println("Spot color converted to CMYK: $spotToCmyk")

Identifying Color Types#

Android exposes color values as a sealed Color hierarchy. Use Kotlin type checks before reading type-specific properties.

val detectedTypes = listOf(srgbColor, cmykColor, spotColor).map { color ->
    when (color) {
        is RGBAColor -> "sRGB"
        is CMYKColor -> "CMYK"
        is SpotColor -> "SpotColor"
    }
}

This lets you branch on RGBAColor, CMYKColor, and SpotColor before reading their component properties.

Handling Tint and Alpha#

Alpha controls transparency. Tint controls color strength. Non-black sRGB colors convert to CMYK with tint = 1.0, even if the source has alpha. Pure black sRGB uses the source alpha as the CMYK tint.

CMYK and spot colors convert to opaque sRGB previews. In Managed scenes, CMYK tint scales the ink values before profile conversion. Legacy scenes blend the converted RGB components toward white. RGB spot approximations blend toward white in both modes.

When converting a spot color to CMYK, a registered CMYK approximation retains its tint. In Managed scenes, RGB-only approximations apply tint before profile conversion and return tint = 1.0. Legacy scenes convert RGB-only approximations without applying tint.

Source	Target	Transformation
sRGB alpha (non-black)	CMYK	The converted CMYK color uses `tint = 1.0`
sRGB alpha (pure black)	CMYK	The converted CMYK color uses `tint = source alpha`
CMYK tint	sRGB	Managed scenes scale ink values; Legacy scenes blend RGB toward white. The result is opaque.
SpotColor tint	sRGB	Tint changes the approximation; the result is opaque.
SpotColor tint	CMYK	CMYK approximations retain tint. Managed RGB-only approximations apply tint before conversion and return `tint = 1.0`.

The sample below uses a non-black transparent sRGB color, so its converted CMYK color keeps tint = 1.0.

val transparentSrgb = Color.fromRGBA(r = 0.2F, g = 0.4F, b = 0.9F, a = 0.5F)
val transparentSrgbToCmyk = engine.editor.convertColorToColorSpace(
    color = transparentSrgb,
    colorSpace = ColorSpace.CMYK,
) as CMYKColor

val tintedCmyk = Color.fromCMYK(c = 0F, m = 0.8F, y = 0.95F, k = 0F, tint = 0.5F)
val tintedCmykPreview = engine.editor.convertColorToColorSpace(
    color = tintedCmyk,
    colorSpace = ColorSpace.SRGB,
) as RGBAColor

val tintedSpotColor = Color.fromSpotColor(
    name = "Brand Red",
    tint = 0.4F,
    externalReference = "",
)
val tintedSpotPreview = engine.editor.convertColorToColorSpace(
    color = tintedSpotColor,
    colorSpace = ColorSpace.SRGB,
) as RGBAColor
val tintedSpotToCmyk = engine.editor.convertColorToColorSpace(
    color = tintedSpotColor,
    colorSpace = ColorSpace.CMYK,
) as CMYKColor

Practical Use Cases#

Building a Color Picker#

When a custom color picker needs screen preview values, convert the design color to sRGB and display the returned RGBAColor components.

val colorFromDesign: Color = spotColor
val pickerPreviewColor = engine.editor.convertColorToColorSpace(
    color = colorFromDesign,
    colorSpace = ColorSpace.SRGB,
) as RGBAColor
// Display pickerPreviewColor.r, pickerPreviewColor.g, pickerPreviewColor.b, and pickerPreviewColor.a.

Export Preparation#

Before a print-oriented export, check whether the color is already CMYK. Convert non-CMYK colors to ColorSpace.CMYK before showing or storing print values.

val colorForExport: Color = srgbColor
val printColor = if (colorForExport is CMYKColor) {
    colorForExport
} else {
    engine.editor.convertColorToColorSpace(
        color = colorForExport,
        colorSpace = ColorSpace.CMYK,
    ) as CMYKColor
}

Troubleshooting#

Issue	Cause	Solution
Spot color converts to an unexpected value	The spot color has no approximation for the target color space	Call `setSpotColor(...)` with an `RGBAColor` or `CMYKColor` before conversion
Colors differ after round-tripping	Color conversion is not always lossless	Avoid assuming that converting sRGB to CMYK and back returns the exact original value
Type-specific properties are unavailable	`convertColorToColorSpace(...)` returns the base `Color` type	Cast after converting, or check the type with Kotlin `is` checks

API Reference#

API	Purpose
`engine.editor.convertColorToColorSpace(color=_, colorSpace=_)`	Converts a color to `ColorSpace.SRGB` or `ColorSpace.CMYK`
`engine.editor.setSpotColor(name=_, color=Color.fromRGBA(r=_, g=_, b=_, a=_))`	Defines or updates an RGB approximation for a spot color
`engine.editor.setSpotColor(name=_, color=Color.fromCMYK(c=_, m=_, y=_, k=_, tint=_))`	Defines or updates a CMYK approximation for a spot color
`Color.fromRGBA(r=_, g=_, b=_, a=_)`	Creates an sRGB color value
`Color.fromCMYK(c=_, m=_, y=_, k=_, tint=_)`	Creates a CMYK color value
`Color.fromSpotColor(name=_, tint=_, externalReference=_)`	Creates a spot color reference that uses the registered approximation for its name