After I have downloaded my component, I have made the following changes in order to get the images being shown in the frontend as well as in the backend:
IN THE BACKEND:
1. Change in imagepicker.php
administrator -> components -> your_component -> dom -> html -> form -> input -> file -> imagepicker.php
In the function function jsPicker() delete the [images]-Tag and change the line from
$indirectUrl = JURI::base(true) . "/index.php?option=" . $this->getExtension() . "&task=file&path=[IMAGES]";
to
$indirectUrl = JURI::base(true) . "/index.php?option=" . $this->getExtension() . "&task=file&path=";
2. Change in insert.js
administrator -> components -> your_component -> dom -> assets -> imagepicker -> js -> insert.js
change the lines 9 AND 19 from
[Line 9 ] var src = fieldData.url + path;
[Line 19] $(field).value = '[IMAGES]' + path
to
[Line 9 ] var src = fieldData.url + '../' + path;
[Line 19] $(field).value = path
###############################################################
IN THE FRONTEND:
Either you make the changes in the core template files or (better) in the template override files, change the root-attribute and replace the [DIR_+++_+++] in the JDom->html.fly.file whereever you want the image to be displayed:
From for example:
JDom::_('html.fly.file', array(
'dataKey' => 'photo',
...
...
...
...
'root' => '[DIR_+++_+++]',
));
To:
JDom::_('html.fly.file', array(
'dataKey' => 'photo',
...
...
...
...
'root' => ''
));