Probleme avec phpthumbs

All attempts to create GD image source failed.
ImageMagick is not installed (it is highly recommended that you install it).
Source image is too large (4368x2912 = 12.7Mpx, max=6.7Mpx) for GD creation (either install ImageMagick or increase PHP memory_limit to at least 69M).

phpThumb() v1.7.9-200805132119 in file "phpthumb.class.php" on line 218

setSourceFilename(/web/lebijou/www/newbijou/components/com_flexicontent/uploads/karimouche-2.jpg) set $this->sourceFilename to "/web/lebijou/www/newbijou/components/com_flexicontent/uploads/karimouche-2.jpg" in file "phpthumb.class.php" on line 245

file_exists() = 0 in file "phpthumb.class.php" on line 1107

is_executable() = 0 in file "phpthumb.class.php" on line 1108

ImageMagickThumbnailToGD() aborting because cannot find convert in $this->config_imagemagick_path (), and `which convert` returned () in file "phpthumb.class.php" on line 1137

$AvailableImageOutputFormats = array(text;ico;bmp;wbmp;gif;png;jpeg) in file "phpthumb.class.php" on line 890

$this->thumbnailFormat set to $this->config_output_format "jpeg" in file "phpthumb.class.php" on line 901

$this->thumbnailQuality set to "80" in file "phpthumb.class.php" on line 918

$this->sourceFilename set to "/web/lebijou/www/newbijou/components/com_flexicontent/uploads/karimouche-2.jpg" in file "phpthumb.class.php" on line 819

setCacheDirectory() starting with config_cache_directory = "" in file "phpthumb.class.php" on line 925

$this->config_cache_directory () is not a directory in file "phpthumb.class.php" on line 961

SetCacheFilename() failed because $this->config_cache_directory is empty in file "phpthumb.class.php" on line 3078

starting ExtractEXIFgetImageSize() in file "phpthumb.class.php" on line 2922

GetImageSize(/web/lebijou/www/newbijou/components/com_flexicontent/uploads/karimouche-2.jpg) says image is 4368x2912 in file "phpthumb.class.php" on line 2932

$this->useRawIMoutput=true after checking $UnAllowedParameters in file "phpthumb.class.php" on line 1254

ImageMagickThumbnailToGD() aborting because ImageMagickCommandlineBase() failed in file "phpthumb.class.php" on line 1893

ImageMagickThumbnailToGD() failed in file "phpthumb.class.php" on line 2968

SetOrientationDependantWidthHeight() starting with "4368"x"2912" in file "phpthumb.class.php" on line 2901

SetOrientationDependantWidthHeight() setting w="600", h="600" in file "phpthumb.class.php" on line 2917

EXIF thumbnail extraction: (size=3652; type="2"; 160x106) in file "phpthumb.class.php" on line 3017

image is 4368x2912 and therefore contains more pixels (12719616) than $this->config_max_source_pixels setting (6710886) in file "phpthumb.class.php" on line 3059

starting SourceImageToGD() in file "phpthumb.class.php" on line 3275

$this->useRawIMoutput=true after checking $UnAllowedParameters in file "phpthumb.class.php" on line 1254

ImageMagickThumbnailToGD() aborting because ImageMagickCommandlineBase() failed in file "phpthumb.class.php" on line 1893

Not using EXIF thumbnail data because $this->config_use_exif_thumbnail_for_speed is FALSE in file "phpthumb.class.php" on line 3343

$this->gdimg_source is still empty in file "phpthumb.class.php" on line 3383

ImageMagickThumbnailToGD() failed in file "phpthumb.class.php" on line 3385

phpThumb() v1.7.9-200805132119

All attempts to create GD image source failed.
ImageMagick is not installed (it is highly recommended that you install it).
Source image is too large (4368x2912 = 12.7Mpx, max=6.7Mpx) for GD creation (either install ImageMagick or increase PHP memory_limit to at least 69M). in file "phpthumb.class.php" on line 3711

phpThumb() v1.7.9-200805132119

Image (JPEG) is too large for PHP-GD memory_limit, please install ImageMagick or increase php.ini memory_limit setting in file "phpthumb.class.php" on line 3711

SourceImageToGD() failed in file "phpthumb.class.php" on line 325

All attempts to create GD image source failed.
...
Source image is too large (4368x2912 = 12.7Mpx, max=6.7Mpx) for GD creation (either install ImageMagick or increase PHP memory_limit to at least 69M).