Would it be possible to add support to change the way gridlines are rendered when using sheet.toImage? As they render at the moment they seem quite prominent compared to cell borders.
Well, the worksheet’s gridlines would be rendered same as you look the gridlines when viewing the sheet in print preview mode.
For setting/changing gridlines’ color, if you could change it in MS Excel, you may do it with Aspose.Cells and I am not sure if this is possible even in MS Excel.
I think you may use borders to set your desired line styles (line style, colors etc.) for your worksheets cells, see the topic for reference:
Create Table by Using Border Lines for a Range