Estoy almacenando firmas (usandosignaturepad en mi base de datosColdfusion/MySQL 5.0.88 y me gustaría mostrar la firma que estoy tomando en un pdf que estoy generando confpdf. Sin embargo no puedo hacerlo funcionar ...

Las firmas se almacenan así:

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Hay una función personalizada incluida en siganturepad (firma a imagen) para convertir lo anterior de nuevo en una imagen. Al igual que:

<?php
require_once '../../signature-to-image.php';
$img = sigJsonToImage(file_get_contents('sig-output.json'));

// Output to browser
header('Content-Type: image/png');
imagepng($img);

imagedestroy($img);
>

Pero si intento esto en mi página de fpdf, la página completa se rompe (supongo que porque quiero incrustar la imagen en una celda, no solo la imagen se envía al navegador) y obtengo esto:

ID de recurso # 10 ‰ PNG IHDRÆ 7Ø7 ¢ ¶ ± IDATxœí ›iP [× Ç /’ a6 ± £ 'ŒÀk0 ›ëÝ † 6) NÒÆ ‰ ݸµM2î´nf:“ d2gq “Æušq – Ió! ŽSâÄNJgRÛñ '@ 1KOff ± õ´ ÀfÖÖ /} y'Ä`çþ> x¬û®Gºÿ {Î = ç… ¹.Pm¡ € Ük @ IA (J B1PRŠ'‚P ”„ b ¤% ¡() Å @ IA (J B1PRŠ'‚P ”„ b ¤% ¡() Å @ IA (J B1PRŠ'‚Pc¡ € üÀðèT³Æ Pa × L '^ z02œ¾Ð ”Ô £ · Œ + ÔX‹ S¨0íÍb¼ «wpåòô4, h ¤vK † ê¿Õe¨þÆà1Á óÓ ¥ bŽTÌÉËN ™ ÃL # u ªƒÇ • ¾§Y '± 27½ZÂg% {^ ƒ? Œ NÚoQ¨ ° A † ê ‡ ‡ F ‡ ‡ ‡ ‡ ½ ‡ ‡ ½ ‡ ½ ‡ ½ ‡ ‡ ½ ‡ ‡ ½ /Ëy4Z1%*lvG{¹YmÀãÚØATTmÆiþ‹i|êN}c÷7}ß´öûiêoÖ×dº-¹'garVÛSïž?)ïTKxÏ?.‰aFø˜ßÞcúJ¡¯−¼>:y° ˆˆˆ÷> kÙ ‰ 1øÕ »XR £“ wZԘŠ”Zà · Z £ ÛUuíîäø¨y6iÒjSjJA † êÛºMV› ƒ¸ÄCX "Äîppa de vajilla de las piezas de la mesa de recambio para la pesca de las gomas de los animales de la prenda de la prenda de recambio. + ^ Ýý3 | ü® "" idâí / ÛjOw: œ ^ fkɳ [KçÁ˜'qk ‹ÚЬ6ÈP} WŸÅîpâãaa @ ÌM – ˆ2 [* æho¿ö ™ RŽbÀo1án © ®AõÝõA |„ ‡ ...

Si estoy haciendo esto:

if( strlen($unterschrift) > 0){
    $img = sigJsonToImage( $unterschrift );
};

y tratar de dar salida:

if ( $imgProceed == "true" ){
    $pdf->imagepng($img);
} else {
    $pdf->Cell(50,4,'',0,1);
}

todo lo que estoy consiguiendo es:

`Call to undefined method PDF::imagepng() `/ `strpos() expects parameter 1 to be string, resource` 

¿Puede alguien explicarme, qué estoy haciendo mal o qué debo hacer para incluir la imagen en una celda en el fpdf? No tengo ni idea

¡Gracias!