Question: Frans Luycx became the leading portrait painter to which Emperor?

full_context: Document 1: Frans Denys: Frans Denys (name variations: François de Nijs, François de Nis, François de Nys, François Denis, François Denys, François Dannys, François Nijs, Fransois Denies, Donys; first name also: Fransoos and Fransous) (c. 1610, Antwerp – 1670, Mantua), was a Flemish Baroque painter mainly of portraits. After a successful career in Antwerp he became a court painter in Italy.
Document 2: Ferdinand III, Holy Roman Emperor: Ferdinand III (13 July 1608 – 2 April 1657) was Holy Roman Emperor from 15 February 1637 until his death, as well as King of Hungary and Croatia, King of Bohemia and Archduke of Austria. He was the last emperor to have real power over the Holy Roman Empire.
Document 3: House of Habsburg: The House of Habsburg ( ; ] ), also called House of Austria, was one of the most influential and outstanding royal houses of Europe. The throne of the Holy Roman Empire was continuously occupied by the Habsburgs between 1438 and 1740. The house also produced emperors and kings of the Kingdom of Bohemia, Kingdom of England ("Jure uxoris" King), Kingdom of Germany, Kingdom of Hungary, Kingdom of Croatia, Second Mexican Empire, Kingdom of Ireland ("Jure uxoris" King), Kingdom of Portugal, and Spain, as well as rulers of several Dutch and Italian principalities. From the 16th century, following the reign of Charles V, the dynasty was split between its Austrian and Spanish branches. Although they ruled distinct territories, they nevertheless maintained close relations and frequently intermarried.
Document 4: Ferdinand I, Holy Roman Emperor: Ferdinand I (Spanish: "Fernando I" ) (10 March 1503 – 25 July 1564) was Holy Roman Emperor from 1558, king of Bohemia and Hungary from 1526, and king of Croatia from 1527 until his death. Before his accession, he ruled the Austrian hereditary lands of the Habsburgs in the name of his elder brother, Charles V, Holy Roman Emperor. Also, he often served as Charles' representative in Germany and developed useful relationships with German princes.
Document 5: Joseph Ducreux: Joseph, Baron Ducreux (26 June 1735 – 24 July 1802) was a French noble, portrait painter, pastelist, miniaturist, and engraver, who was a successful portraitist at the court of Louis XVI of France, and resumed his career after the French Revolution. He was made a baron and "premier peintre de la reine" (First Painter to the Queen), and drew the last portrait ever made of Louis XVI before the king’s execution. His less formal portraits reflect his fascination with physiognomy and show an interest in expanding the range of facial expressions beyond those of official portraiture.
Document 6: Maximilian I, Holy Roman Emperor: Maximilian I (22 March 1459 – 12 January 1519) was King of the Romans (also known as King of the Germans) from 1486 and Holy Roman Emperor from 1493 until his death, though he was never crowned by the Pope, as the journey to Rome was always too risky. He was the son of Frederick III, Holy Roman Emperor, and Eleanor of Portugal. He ruled jointly with his father for the last ten years of his father's reign, from c. 1483 to 1493.
Document 7: Portrait painting in Scotland: Portrait painting in Scotland includes all forms of painted portraiture in Scotland, from its beginnings in the early sixteenth century until the present day. The origins of the tradition of portrait painting in Scotland are in the Renaissance, particularly through contacts with the Netherlands. The first portrait of a named person that survives is that of Archbishop William Elphinstone, probably painted by a Scottish artist using Flemish techniques around 1505. Around the same period Scottish monarchs turned to the recording of royal likenesses in panel portraits, painted in oils on wood. The tradition of royal portrait painting in Scotland was probably disrupted by the minorities and regencies it underwent for much of the sixteenth century. It began to flourish after the Reformation, with paintings of royal figures and nobles by Netherlands artists Hans Eworth, Arnold Bronckorst and Adrian Vanson. A specific type of Scottish picture from this era was the "vendetta portrait", designed to keep alive the memory of an atrocity. The Union of Crowns in 1603 removed a major source of artistic patronage in Scotland as James VI and his court moved to London. The result has been seen as a shift "from crown to castle", as the nobility and local lairds became the major sources of patronage.
Document 8: Ferdinand, Duke of Breisgau: Archduke Ferdinand Karl of Austria-Este (1 June 1754 – 24 December 1806) was a son of Holy Roman Emperor Franz I and Maria Theresa of Austria. He was the founder of the House of Austria-Este and Governor of the Duchy of Milan between 1765 and 1796. He was also designated as the heir to the Duchy of Modena and Reggio, but he never reigned, owing to the Napoleonic Wars.
Document 9: Frans Luycx: Frans Luycx or Frans Luyckx (before 17 April 1604 – 1 May 1668) was a Flemish painter who became the leading portrait painter at the imperial court of Emperor Ferdinand III in Vienna. He is best known for his portraits of the Emperor's family and various members of the Habsburgers, including its Austrian and Spanish branches.
Document 10: Otto Heinrich Fugger, Count of Kirchberg: Otto Heinrich Fugger, Count of Kirchberg and Weissenhorn (1592–1644) was promoted to be a Knight of the Order of the Golden Fleece in 1628. He was the son of Christoph Fugger von Glött, deceased 1615, the grandson of Johann Fugger, deceased 1598, the great grandson of very wealthy Augsburg city International businessman and banker Anton Fugger (1493–1560). The 16th century Fugger's, descendents of a German businessmen family tracked down to the 14th century, were the Imperial bankers with King Charles I of Imperial Spain, also Holy Roman Emperor as Charles V (1500–1558), and his brother, also Holy Roman Emperor, Ferdinand I of Habsburg (1503–1564), king of Hungary and Bohemia from 1526, emperor from 1556 by abdication of his brother Charles.
Document 11: Frans van Mieris the Elder: Frans van Mieris, the elder (16 April 1635 – 12 March 1681), was a Dutch Golden Age genre and portrait painter. The leading member of a Leiden family of painters, his sons Jan (1660–1690) and Willem (1662–1747) and his grandson Frans van Mieris the Younger (1689–1763) were also accomplished genre painters.
Document 12: Rudolf II, Holy Roman Emperor: Rudolf II (18 July 1552 – 20 January 1612) was Holy Roman Emperor (1576–1612), King of Hungary and Croatia (as Rudolf I, 1572–1608), King of Bohemia (1575–1608/1611) and Archduke of Austria (1576–1608). He was a member of the House of Habsburg.
Document 13: Leopold I, Holy Roman Emperor: Leopold I (name in full: "Leopold Ignaz Joseph Balthasar Felician"; Hungarian: "I. Lipót" ; 9 June 1640 – 5 May 1705) was Holy Roman Emperor, King of Hungary, Croatia, and Bohemia. The second son of Ferdinand III, Holy Roman Emperor, by his first wife, Maria Anna of Spain, Leopold became heir apparent in 1654 by the death of his elder brother Ferdinand IV. Elected in 1658, Leopold ruled the Holy Roman Empire until his death in 1705.
Document 14: Lucas Vorsterman: Lucas Vorsterman (1595–1675) was a Baroque engraver. He worked with the artists Peter Paul Rubens and Anthony van Dyck, as well as for patrons such as Thomas Howard, 21st Earl of Arundel and Charles I of England.
Document 15: Holy Roman Empire: The Holy Roman Empire (Latin: "Sacrum Imperium Romanum" ; German: "Heiliges Römisches Reich" ) was a multi-ethnic complex of territories in central Europe that developed during the Early Middle Ages and continued until its dissolution in 1806. The largest territory of the empire after 962 was the Kingdom of Germany, though it also came to include the Kingdom of Bohemia, the Kingdom of Burgundy, the Kingdom of Italy, and numerous other territories.
ground_truth: Ferdinand III