A Forfar man superimposed photographs of his face and the faces of children on to images of “vile” sexual acts.
John Myles, 51, also annotated the images with descriptions of his sick fantasies, Dundee Sheriff Court heard.
The paedophile had a total of 4,001 indecent images of children aged between five and 15 in his possession, some of which had been modified with the use of photo editing software.
The most extreme images were classed as category A.
Myles, a first offender, was said to have been employed in a “responsible” job, which he was hoping to continue with.
However, Sheriff Alastair Brown revoked his bail and remanded him in custody to await sentencing.
Sheriff Brown said: “The research tells us that those who have downloaded this kind of material – and who only do that as their first offence – are exceptionally unlikely to go on and actually touch a child.
“You, however, have adapted the images and annotated them with narrative.
“The images are vile and there is quite a lot of material.
“The use of images of real children moves your conduct into a different realm.”
In Myles’ defence, the court heard he had been searching for something “legitimate” when he found the images of child abuse, which “whetted his appetite”.
He was also said to have an interest in photoshop, which apparently led him to edit the photos.
Myles, of Caledonian Way, Whitehills, pled guilty to possessing indecent images of children between November 12 2013 and July 25 2018, at Mount Feredith in Forfar.
He also admitted taking, or permitting to be taken, indecent images of children between November 12 2013 and July 8 2018, at the same address.
Myles had his sentence deferred until May 21 for criminal justice and social work reports.