ArcGISDynamicMapServiceLayer showing white pixels as transparent even though black pixels are supposed to be background

[IsaacBoates]

We are visualizing a tiff image in our web map.  We have set the layer properties to say that black pixels are to be treated as background, and that they should be displayed as transparent.  Visualizing it in ArcGIS Desktop confirms that this is working properly.  However, as soon as the layer is published and the layer is put into a ArcGISDynamicMapServiceLayer, the white pixels seem to become transparent.  We cannot seem to identify the cause of this problem.

This is the code (SETTLE_VP_ORTHOPHOTO is a variable storing the rest endpoint for the layer.):

var VP_ortho = new ArcGISDynamicMapServiceLayer(SETTLE_VP_ORTHOPHOTO ,{
    id: "VP_ortho",
    visible: false
});

This is the service layer definition:

Layer: mos_VP_2.tif (ID: 0)

Name: mos_VP_2.tifDisplay Field:Type: Raster LayerGeometry Type: nullDescription: Definition Expression: N/ACopyright Text: Default Visibility: true MaxRecordCount: 0Supported Query Formats: JSON, AMF, geoJSONMin Scale: 0Max Scale: 0Supports Advanced Queries: falseSupports Statistics: falseHas Labels: falseCan Modify Layer: falseCan Scale Symbols: falseUse Standardized Queries: trueExtent:

XMin: 2065234.8595104713

YMin: 6195018.263458403

XMax: 2068324.6069604708

YMax: 6199050.734858402

Spatial Reference: 102100  (3857)

Drawing Info:

N/A

Advanced Query Capabilities:

Supports Statistics: false

Supports OrderBy: false

Supports Distinct: false

Supports Pagination: false

Supports TrueCurve: false

Supports Returning Query Extent: true

Supports Query With Distance: true

Supports Sql Expression: false

HasZ: false HasM: false Has Attachments: falseHTML Popup Type: esriServerHTMLPopupTypeNoneType ID Field: nullFields: None