How to read pictures while reading all data

[jamninetyfive]

when i read data i get empty string

    for row in 1..max_col_and_row.0+1 {
        let mut row_vec: Vec<String> = Vec::new();
        for col in 1..max_col_and_row.1+1 {
            let cell = book
                .get_sheet_by_name(sheetname)
                .expect(&format!("Unable to open sheet: {}", sheetname))
                .get_value((row, col));
            row_vec.push(cell);
        }
        container.push(row_vec);
    }

or can I get cellType like stream, string, number....

What I want to get all data including image data and convert it to base64 and return it for use.