diff --git a/contrib/HDRMerge.lua b/contrib/HDRMerge.lua
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+--[[HDRMerge plugin for darktable
+
+  copyright (c) 2018  Kevin Ertel
+  
+  darktable is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+  
+  darktable is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+  
+  You should have received a copy of the GNU General Public License
+  along with darktable.  If not, see <http://www.gnu.org/licenses/>.
+]]
+
+--[[About this Plugin
+This plugin adds the module 'HDRMerge' to darktable's lighttable view
+
+----REQUIRED SOFTWARE----
+HDRMerge ver. 4.5 or greater
+
+----USAGE----
+Install: (see here for more detail: https://github.com/darktable-org/lua-scripts )
+ 1) Copy this file in to your 'lua/contrib' folder where all other scripts reside. 
+ 2) Require this file in your luarc file, as with any other dt plug-in
+On the initial startup go to darktable settings > lua options and set your executable paths and other preferences, then restart darktable
+
+Select bracketed images and press the Run HDRMerge button. The resulting DNG will be auto-imported into darktable.
+Additional tags or style can be applied on auto import as well, if you desire.
+
+Base Options:
+Select your desired BPS (bits per sample and Embedded Preview Size. 
+
+Batch Options:
+Select if you want to run in batch mode or not
+Select the gap, in seconds, between images for auto grouping in batch mode
+
+See HDRMerge manual for further detail: http://jcelaya.github.io/hdrmerge/documentation/2014/07/11/user-manual.html
+
+Auto-import Options:
+Select a style, whether you want tags to be copied from the original, and any additional tags you desire added when the new image is auto-imported
+]]
+
+local dt = require 'darktable'
+local df = require 'lib/dtutils.file'
+local dsys = require 'lib/dtutils.system'
+local mod = 'module_HDRMerge'
+local os_path_seperator = '/'
+if dt.configuration.running_os == 'windows' then os_path_seperator = '\\' end
+
+-- Tell gettext where to find the .mo file translating messages for a particular domain
+local gettext = dt.gettext
+gettext.bindtextdomain('HDRMerge',dt.configuration.config_dir..'/lua/locale/')
+local function _(msgid)
+    return gettext.dgettext('HDRMerge', msgid)
+end
+
+local temp
+local HDRM = { --HDRMerge Program Table
+    name = 'HDRMerge',
+    bin = '',
+    first_run = true,
+    install_error = false,
+    arg_string = '',
+    images_string = '',
+    args = {
+        bps         ={text = '-b ', style = 'integer'},
+        size        ={text = '-p ', style = 'string'},
+        batch       ={text = '-B ', style = 'bool'},
+        gap         ={text = '-g ', style = 'integer'}
+    }
+}
+local GUI = { --GUI Elements Table
+    HDR = {
+        bps         ={},
+        size        ={},
+        batch       ={},
+        gap         ={}
+    },
+    Target = {
+        style       ={},
+        copy_tags   ={},
+        add_tags    ={}
+    },
+    run = {},
+    stack = {},
+    options = {},
+    exes = {
+        HDRMerge = {},
+        update = {},
+    }
+}
+
+--Detect User Styles--
+local styles = dt.styles
+local styles_count = 1 -- 'none' = 1
+for _,i in pairs(dt.styles) do
+    if type(i) == 'userdata' then styles_count = styles_count + 1 end
+end
+
+local function InRange(test, low, high) --tests if test value is within range of low and high (inclusive)
+    if test >= low and test <= high then
+        return true
+    else
+        return false
+    end
+end
+
+local function GetFileName(full_path) --Parses a full path (path/filename_identifier.extension) into individual parts
+--[[Input: Folder1/Folder2/Folder3/Img_0001.CR2
+    
+    Returns:
+    path: Folder1/Folder2/Folder3/
+    filename: Img_0001
+    identifier: 0001
+    extension: .CR2
+    
+    EX:
+    path_1, file_1, id_1, ext_1 = GetFileName(full_path_1)
+    ]]
+    local path = string.match(full_path, '.*[\\/]')
+    local filename = string.gsub(string.match(full_path, '[%w-_]*%.') , '%.' , '' ) 
+    local identifier = string.match(filename, '%d*$')
+    local extension = string.match(full_path, '%.%w*')
+    return path, filename, identifier, extension
+end
+
+local function CleanSpaces(text) --removes spaces from the front and back of passed in text
+    text = string.gsub(text,'^%s*','')
+    text = string.gsub(text,'%s*$','')
+    return text
+end
+
+local function BuildExecuteCmd(prog_table) --creates a program command using elements of the passed in program table
+    local result = CleanSpaces(prog_table.bin)..' '..CleanSpaces(prog_table.arg_string)..' '..CleanSpaces(prog_table.images_string)
+    return result
+end
+
+local function PreCall(prog_tbl) --looks to see if this is the first call, if so checks to see if program is installed properly
+    for _,prog in pairs(prog_tbl) do
+        if prog.first_run then
+            prog.bin = df.check_if_bin_exists(prog.name)
+            if not prog.bin then 
+                prog.install_error = true
+                dt.preferences.write(mod, 'bin_exists', 'bool', false)
+            else
+                prog.bin = CleanSpaces(prog.bin)
+            end
+            prog.first_run = false
+        end
+    end
+    if not dt.preferences.read(mod, 'bin_exists', 'bool') then
+        GUI.stack.active = 2
+        dt.print(_('please update you binary locatoin'))
+    end
+end
+
+local function ExeUpdate(prog_tbl)
+    dt.preferences.write(mod, 'bin_exists', 'bool', true)
+    for _,prog in pairs(prog_tbl) do
+        dt.preferences.write('executable_paths', prog.name, 'string', GUI.exes[prog.name].value)
+        prog.bin = df.check_if_bin_exists(prog.name)
+        if not prog.bin then 
+            prog.install_error = true
+            dt.preferences.write(mod, 'bin_exists', 'bool', false)
+        else
+            prog.bin = CleanSpaces(prog.bin)
+        end
+        prog.first_run = false
+    end
+    if dt.preferences.read(mod, 'bin_exists', 'bool') then
+        GUI.stack.active = 1
+        dt.print(_('update successful'))
+    else
+        dt.print(_('update unsuccessful, please try again'))
+    end
+end
+
+local function UpdateActivePreference() --sliders & entry boxes do not have a click/changed callback, so their values must be saved to the active preference
+    temp = GUI.HDR.gap.value
+    dt.preferences.write(mod, 'active_gap', 'integer', temp)
+    temp = GUI.Target.add_tags.text
+    dt.preferences.write(mod, 'active_add_tags', 'string', temp)
+end
+
+local function main()
+    PreCall({HDRM}) --check if furst run then check if install OK
+    if HDRM.install_error then
+        dt.print_error(_('HDRMerge install issue'))
+        dt.print(_('HDRMerge install issue, please ensure the binary path is proper'))
+        return
+    end
+    images = dt.gui.selection() --get selected images
+    if #images < 2 then --ensure enough images selected
+        dt.print(_('not enough images selected, select at least 2 images to merge'))
+        return
+    end
+    
+    UpdateActivePreference() --save current gui elements to active preference so those values will be pre-loaded at next startup
+    
+    --create image string and output path
+    HDRM.images_string = ''
+    local out_path = ''
+    local smallest_id = math.huge
+    local smallest_name = ''
+    local largest_id  = 0
+    local source_raw = {}
+    for _,image in pairs(images) do --loop to concat the images string, also track the image indexes for use in creating the final image name (eg; IMG_1034-1037.dng)
+        local curr_image = image.path..os_path_seperator..image.filename
+        HDRM.images_string = HDRM.images_string..df.sanitize_filename(curr_image)..' '
+        out_path = image.path
+        _, source_name, source_id = GetFileName(image.filename)
+        source_id = tonumber(source_id)
+        if source_id < smallest_id then 
+            smallest_id = source_id
+            smallest_name = source_name
+            source_raw = image
+        end
+        if source_id > largest_id then largest_id = source_id end
+    end
+    out_path = out_path..os_path_seperator..smallest_name..'-'..largest_id..'.dng'
+    out_path = df.create_unique_filename(out_path)
+    
+    --create argument string
+    HDRM.arg_string = HDRM.args.bps.text..GUI.HDR.bps.value..' '..HDRM.args.size.text..GUI.HDR.size.value..' '
+    if GUI.HDR.batch.value then 
+        HDRM.arg_string = HDRM.arg_string..HDRM.args.batch.text..HDRM.args.gap.text..math.floor(GUI.HDR.gap.value)..' -a'
+    else
+        HDRM.arg_string = HDRM.arg_string..'-o '..df.sanitize_filename(out_path)
+    end
+    
+    -- create run command and execute
+    local run_cmd = BuildExecuteCmd(HDRM)
+    resp = dsys.external_command(run_cmd)
+    
+    if resp == 0 and not GUI.HDR.batch.value then
+        local imported = dt.database.import(out_path) -- import the new file
+        if GUI.Target.style.selected > 1 then -- apply selected style
+            local set_style = styles[GUI.Target.style.selected - 1]
+            dt.styles.apply(set_style , imported)
+        end
+        if GUI.Target.copy_tags.value then -- copy tags from the original file (ignore 'darktable' generated tags)
+            local all_tags = dt.tags.get_tags(source_raw) 
+            for _,tag in pairs(all_tags) do
+                if string.match(tag.name, 'darktable|') == nil then dt.tags.attach(tag, imported) end
+            end
+        end
+        local set_tag = GUI.Target.add_tags.text
+        if set_tag ~= nil then -- add additional user-specified tags
+            for tag in string.gmatch(set_tag, '[^,]+') do
+                tag = CleanSpaces(tag)
+                tag = dt.tags.create(tag)
+                dt.tags.attach(tag, imported) 
+            end
+        end
+        dt.print(_('HDRMerge completed successfully'))
+    else
+        dt.print_error(_('HDRMerge failed'))
+        dt.print(_('HDRMerge failed'))
+    end
+
+end
+
+-- GUI Elements --
+local lbl_hdr = dt.new_widget('section_label'){
+    label = _('HDRMerge options')
+}
+temp = dt.preferences.read(mod, 'active_bps_ind', 'integer')
+if not InRange(temp, 1, 3) then temp = 3 end 
+GUI.HDR.bps = dt.new_widget('combobox'){
+    label = _('bits per sample'), 
+    tooltip =_('number of bits per sample in the output image'),
+    selected = temp,
+    '16','24','32',             
+    changed_callback = function(self)
+        dt.preferences.write(mod, 'active_bps', 'integer', self.value) 
+        dt.preferences.write(mod, 'active_bps_ind', 'integer', self.selected)
+    end,
+    reset_callback = function(self) 
+        self.selected = 3
+        dt.preferences.write(mod, 'active_bps', 'integer', self.value) 
+        dt.preferences.write(mod, 'active_bps_ind', 'integer', self.selected)
+    end
+} 
+temp = dt.preferences.read(mod, 'active_size_ind', 'integer')
+if not InRange(temp, 1, 3) then temp = 2 end 
+GUI.HDR.size = dt.new_widget('combobox'){
+    label = _('embedded preview size'), 
+    tooltip =_('size of the embedded preview in output image'),
+    selected = temp,
+    _('none'),_('half'),_('full'),             
+    changed_callback = function(self)
+        dt.preferences.write(mod, 'active_size', 'string', self.value) 
+        dt.preferences.write(mod, 'active_size_ind', 'integer', self.selected)
+    end,
+    reset_callback = function(self) 
+        self.selected = 2
+        dt.preferences.write(mod, 'active_size', 'string', self.value) 
+        dt.preferences.write(mod, 'active_size_ind', 'integer', self.selected)
+    end
+} 
+GUI.HDR.batch = dt.new_widget('check_button'){
+    label = _('batch mode'),
+    value = dt.preferences.read(mod, 'active_batch', 'bool'),
+    tooltip = _('enable batch mode operation \nNOTE: resultant files will NOT be auto-imported'),
+    clicked_callback = function(self)
+        dt.preferences.write(mod, 'active_batch', 'bool', self.value)
+        GUI.HDR.gap.sensitive = self.value
+    end,
+    reset_callback = function(self) self.value = false end
+}
+temp = dt.preferences.read(mod, 'active_gap', 'integer')
+if not InRange(temp, 1, 3600) then temp = 3 end
+GUI.HDR.gap = dt.new_widget('slider'){
+    label = _('batch gap [sec.]'),
+    tooltip = _('gap, in seconds, between batch mode groups'),
+    soft_min = 1,
+    soft_max = 30,
+    hard_min = 1,
+    hard_max = 3600,
+    step = 1,
+    digits = 0,
+    value = temp,
+    sensitive = GUI.HDR.batch.value,
+    reset_callback = function(self) 
+        self.value = 3
+    end
+}
+local lbl_import = dt.new_widget('section_label'){
+    label = _('import options')
+}
+GUI.Target.style = dt.new_widget('combobox'){
+    label = _('apply style on import'),
+    tooltip = _('Apply selected style on auto-import to newly created image'),
+    selected = 1,
+    _('none'),
+    changed_callback = function(self)
+        dt.preferences.write(mod, 'active_style', 'string', self.value) 
+        dt.preferences.write(mod, 'active_style_ind', 'integer', self.selected)
+    end,
+    reset_callback = function(self) 
+        self.selected = 1
+        dt.preferences.write(mod, 'active_style', 'string', self.value) 
+        dt.preferences.write(mod, 'active_style_ind', 'integer', self.selected)
+    end 
+}
+for k=1, (styles_count-1) do
+    GUI.Target.style[k+1] = styles[k].name
+end
+temp = dt.preferences.read(mod, 'active_style_ind', 'integer')
+if not InRange(temp, 1, styles_count) then temp = 1 end
+GUI.Target.style.selected = temp
+GUI.Target.copy_tags = dt.new_widget('check_button'){
+    label = _('copy tags'),
+    value = dt.preferences.read(mod, 'active_copy_tags', 'bool'),
+    tooltip = _('copy tags from first source image'),
+    clicked_callback = function(self) dt.preferences.write(mod, 'active_copy_tags', 'bool', self.value) end,
+    reset_callback = function(self) self.value = true end
+}
+temp = dt.preferences.read(mod, 'active_add_tags', 'string')
+if temp == '' then temp = nil end 
+GUI.Target.add_tags = dt.new_widget('entry'){
+    tooltip = _('Additional tags to be added on import. Seperate with commas, all spaces will be removed'),
+    text = temp,
+    placeholder = _('Enter tags, seperated by commas'),
+    editable = true
+}
+GUI.run = dt.new_widget('button'){
+    label = _('merge'),
+    tooltip =_('run HDRMerge with the above specified settings'),
+    clicked_callback = function() main() end
+}
+GUI.exes.HDRMerge = dt.new_widget('file_chooser_button'){
+    title = _('Select HDRmerge executable'),
+    value = df.get_executable_path_preference(HDRM.name),
+    is_directory = false
+}
+GUI.exes.update = dt.new_widget('button'){
+    label = _('update'),
+    tooltip =_('update the binary path with current value'),
+    clicked_callback = function() ExeUpdate({HDRM}) end
+}
+GUI.options = dt.new_widget('box'){
+    orientation = 'vertical',
+    lbl_hdr,
+    GUI.HDR.bps,
+    GUI.HDR.size,
+    GUI.HDR.batch,
+    GUI.HDR.gap,
+    lbl_import,
+    GUI.Target.style,
+    GUI.Target.copy_tags,
+    GUI.Target.add_tags,
+    GUI.run
+}
+local exes_box = dt.new_widget('box'){
+    orientation = 'vertical',
+    GUI.exes.HDRMerge,
+    GUI.exes.update
+}
+GUI.stack = dt.new_widget('stack'){
+    GUI.options,
+    exes_box
+}
+if dt.preferences.read(mod, 'bin_exists', 'bool') then
+    GUI.stack.active = 1
+else
+    GUI.stack.active = 2
+end
+
+dt.register_lib( -- register HDRMerge module
+    'HDRMerge_Lib', -- Module name
+    _('HDRMerge'), -- name
+    true,   -- expandable
+    true,   -- resetable
+    {[dt.gui.views.lighttable] = {'DT_UI_CONTAINER_PANEL_RIGHT_CENTER', 99}},   -- containers
+    dt.new_widget('box'){
+        orientation = 'vertical',
+        GUI.stack
+        }
+)