TYPO3: Images are rendered with unwanted Outline/Border

In one case i am rendering all images from all news entries from one specific category inside an unordered list. Each image is wrapped inside an anchor element which itself is wrapped inside a list-item. Each image is 100% white and shall be displayed transparent.

After solving a few transparency related issues i now stand before the problem that ALL images are given an outline which i am not aiming for - since in some cases it might clash with the background (the background Image is changing sometimes). Either i have something missing in my code or something is wrong with the images i am trying to use.

Here is the typoscript code used for rendering the images:

myMarker.20 < plugin.tt_news
myMarker.20 
  {
  code >
  code = LIST
  templateFile = fileadmin/templates/ext/tt_news/myMarker_template.html
  excludeAlreadyDisplayedNews = 0

  limit = 6
  categoryMode = 1
  categorySelection = 5
  catImageMode = 0
  catTextMode = 1
  listOrderBy = title asc

  displayList 
    {
    image >
    image.stdWrap.cObject = IMAGE
    image.stdWrap.cObject.linkWrap = <a href="{field:links}" target="_blank">|</a>
    image.stdWrap.cObject.linkWrap.insertData = 1
    image.stdWrap.cObject.titleText.field = title
    image.stdWrap.cObject.file = field:image
    image.stdWrap.cObject.file = GIFBUILDER
    image.stdWrap.cObject.file 
      {
      format = png
      XY = 130, 48
      transparentBackground = 1
      backColor = transparent
      10 = IMAGE  
      10 
        {  
        offset = 0, 48-[10.h]/2
        border = 0
        file 
          {
          import = uploads/pics/  
          import.data = field:image  
          import.listNum = 0  
          import.override.field = image  
          maxW = 130
          maxH = 48
          quality = 100
          }  
        } 
      }
    }
  } # myMarker

Maybe someone has an idea? Thanks for reading/help in advance anyway :)

Solved by not using gifbuilder.