5

i have a geotiff images that have 3bands.

band1,2 is a actual image values and band3 is a instance angle value.

band1,2 is float32 data type

under code is that i try before.

but it doesn't work.

i think band data's range is too large, so it doesn't 

from osgeo import gdal, osr, ogr
from PIL import Image
import numpy as np


ds = gdal.Open('image path', gdal.GA_ReadOnly)
rb = ds.GetRasterBand(1)
test = rb.ReadAsArray()
rb2 = ds.GetRasterBand(2)
test2 = rb2.ReadAsArray()
rb3 = ds.GetRasterBand(3)
test3 = rb3.ReadAsArray()
slice56 = test2
formatted = (slice56 * 255 / np.max(slice56)).astype('uint8')
img = Image.fromarray(formatted)
img.save('save image path')

how can i solve this problem??

송준석
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3 Answers3

11

You can use gdal.Translate for this.

You can read the documentation here

from osgeo import gdal
    
options_list = [
    '-ot Byte',
    '-of JPEG',
    '-b 1',
    '-scale'
]           

options_string = " ".join(options_list)
    
gdal.Translate(
    'save_image_path.jpg',
    'image_path.tif',
    options=options_string
)

The above code simply create a jpg file with band 1 scaled into byte range. You could add more bands by adding, '-b 2' etc. Also notice that scale automatically wraps the entire range into byte range. If you like something else you could use '-scale min_val max_val' in order to specify the range you like, since often you have no need of either the lowest or highest values available.

Pierrick Rambaud
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the_cheff
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2

The above worked well for me except the JPEG resolution wasn't great. Swapping JPEG to PNG worked better.

Overture
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0

I have written the following module and more of that can be found on my GitHub:

import os
from osgeo import gdal

def geotiff_to_png(input_path, output_path=None, return_object=False):
"""
Converts a GeoTIFF file to a PNG file or object. Specific to Skysatimages with 4 bands (blue, green, red, nir).

Args:
    input_path (str): The file path of the input GeoTIFF file.
    output_path (str, optional): The file path of the output PNG file. If not provided, PNG object is returned. Defaults to None.
    return_object (bool, optional): Whether to return the PNG data as an object. If True, the output_path parameter will be ignored. Defaults to False.

Returns:
    numpy.ndarray or None: If output_path is not provided and return_object is True, returns a 3D numpy array representing the PNG image. Otherwise, returns None.

"""
# Open input file
dataset = gdal.Open(input_path)
output_types = [gdal.GDT_Byte, gdal.GDT_UInt16, gdal.GDT_Float32]

# Define output format and options
options = gdal.TranslateOptions(format='PNG', bandList=[3,2,1], creationOptions=['WORLDFILE=YES'], outputType=output_types[0])

# Translate to PNG
if output_path is not None:
    gdal.Translate(output_path, dataset, options=options)
    print(f'Successfully saved PNG file to {output_path}')

# Return PNG object
if return_object:
    mem_driver = gdal.GetDriverByName('MEM')
    mem_dataset = mem_driver.CreateCopy('', dataset, 0)
    png_data = mem_dataset.ReadAsArray()
    return png_data
Sheykhmousa
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