OptionalcompressionThe compression the image was stored for (blip/@cstate): email, screen, print, hqprint, none.
OptionaldpiThe resolution the image is rendered at, in dots per inch (dpi); 0 for the image's own.
Optionalextblip/extLst as the file states it: an opaque DrawingML fragment, written back as it was.
OptionalimageThe adjustments applied to the image itself, as the file states them: the blip's effect
children (lum for brightness and contrast, grayscl, clrChange for a transparent color,
alphaModFix for transparency, biLevel, duotone, …) as one opaque DrawingML fragment,
written back as it was. Not rendered.
OptionalisOptionalresThe resource id of the image.
OptionalsourceThe part of the image used (srcRect), as insets from its edges. Absent for the whole image.
OptionalstretchThe image is stretched to a rectangle inset from the shape's bounds (stretch/fillRect);
{} for the whole shape. Absent when the image is tiled.
OptionaltileThe image is tiled (tile). Absent when it is stretched.
An image fill: a workbook resource stretched over the shape or tiled across it.
Remarks
resIdnames the resource the wayIPicture.JSON.resIdnames a placed picture's image and, like it, is meaningful only inside the persist scope the JSON was made in. A shape resolves it to the resource when it is created and names the resource again when it is serialized.