Picassoでwrap_contentなImageViewに画像を読み込む際に縦横それぞれN倍する ref: https://qiita.com/masaibar/items/7aba5cb506fe652d49e7

ScaleTransformation.kt

class ScaleTransformation(
        private val scale: Float
) : Transformation {

    override fun transform(source: Bitmap?): Bitmap? {
        source ?: return null

        //1倍にするとcreateBitmapしてもsourceを返そうとして死ぬ
        if (scale == 1f) {
            return source
        }

        val matrix = Matrix().apply {
            setScale(
                    scale,
                    scale
            )
        }

        val result = Bitmap.createBitmap(
                source,
                0,
                0,
                source.width,
                source.height,
                matrix,
                true
        )

        source.recycle()

        return result
    }

    override fun key(): String =
            "ScaleTransformation(scale = $scale)"

}

呼び出し元.kt

Picasso.get()
    .load(imageUrl)
    .transform(ScaleTransformation(2f)) //← 倍率を指定
    .into(image_view)