Qt embedded PNG icons not coming properly

Question

I am running a Qt application in IMX6 board.
These are my platform details

• Qt version = QtEmbedded 4.8
• Application type = qml
• Device = IMX6

I have a lot of buttons in my GUI, all are PNG files. The problem is some dark dots/lines are on top of the icon.

But the same icons are working fine in qt-x11.

Icons in Qt-embedded (lines in volume icon and date/time icons)

Icons in Qt-x11 (clear volume icon and date/time icons)

any idea why this is happening?
code snippet: setting icon path for a button

 ButtonImgItem
    {
        id                      : selectID
        objectName              : "SelectBtnID"
        btnWidth                : Math.floor(Const.TYPEC_BUTTON_WIDTH   * Const.X_DPI)
        btnHeight               : Math.floor(Const.TYPEC_BUTTON_HEIGHT  * Const.Y_DPI)
        imagePath               : "../images/e_checkmark_zone2b.png"
        btnTye                  : ApplicationData.BUTTON_TYPE_C
        buttonState             : ApplicationData.BUTTON_STATE_NORMAL
        isCaligned              : true

    anchors.left            : nextBtnID.right
    anchors.leftMargin      : Const.HELP_SELECTGRID_SPACE * Const.X_DPI
    anchors.bottom          : parent.bottom
    anchors.bottomMargin    : Const.HELP_SELECTGRID_BOTTOM_MARIGIN * Const.Y_DPI

    onSignalBtnClicked:
    {
        zone3itemID.enabled = false