Consider the following
With[{img = ExampleData[{"TestImage", "Lena"}]},
Column[{ImageResize[img, 400]}, ItemSize -> {30, 30}, Frame -> All]]
The result is this:
Why is the image, by default, this small size within its bounding area? (The same issue is also true for Grid, but seemingly not for GraphicsGrid.)
The actual size of the image is
In[3]:= ImageDimensions[ExampleData[{"TestImage", "Lena"}]]
Out[3]= {512, 512}
I have tried various options settings for Column and Grid but to no avail.