Encoding .png images to base64 produces several times more data than expected

[ARPasescu]

Godot version: 3.0.6
OS: Windows 10 Pro

Issue description:
I tried encoding several image objects to base64 using Marshalls.variant_to_base64(), and what I found is that the encoding produces several times as as much data as it should on a blank file.

Tested it with a 91 KB image and it resulted in a 186 KB output, 2x the size of the image.
Tested it with a 134 KB image and it resulted in a 470 KB output, 3.5x the size of the image.

The images i was trying to encode are .png files, so I'm not entirely sure whether that plays a role in the file size or whether the output sizes are different for .jpg or other image files, however I ran the same .png files through an online image-to-base64 encoding website (https://www.base64-image.de/) and it produced outputs of 123 KB and 185 KB respectively, both of which corresponding to average estimates for the encoding of about 4/3 times the size of the image. I also tried to get the PoolByteArray raw data from the image object, thinking that it's perhaps encoding non-necessary information together with the image data, but it produced the exact same results.

Steps to reproduce:
Copy this code in a blank project GDScript, add any image you want encoded in base64 to the project and copy its path to the code.

var file = File.new()
var image = Image.new()
image.load("insert any image file path here for encoding")
file.open("temp-file.txt", File.WRITE)
file.store_line(Marshalls.variant_to_base64(image))
file.close()

[bruvzg]

This is expected. Image.load decodes source .png to the OpenGL texture and Marshalls.variant_to_base64 encodes this texture (and other Image metadata).

If you want to encode source .png, load it as File instead of Image.

[ARPasescu]

You are right, I have updated my code to replace Image with File. To get all the data from the image i replaced the store_line parameter with Marshalls.variant_to_base64(image.get_buffer(image.get_len())) and it resulted in a 121 KB file which is exactly 4/3 of the original image size of 91 KB. Thanks for the help.

[LinuxUserGD]

@Rriik So it is fixed?

[ARPasescu]

the respective issue was fixed, however I'm stuck trying to figure out how to then load that saved base64 data onto another image object. I tried this so far

var file = File.new()
var image = File.new()
image.open("res://SamplePNG-100kb.png", File.READ)
file.open("temp-file.txt", File.WRITE)
file.store_line(Marshalls.raw_to_base64(image.get_buffer(image.get_len())))
file.close()

file.open("temp-file.txt", File.READ)
var load_data = file.get_as_text()
var result = Image.new()
result.load_png_from_buffer(Marshalls.base64_to_raw(load_data))
file.close()

However, it gives me an error saying J[30]Y[00]: invalid chunk type and then says the png is corrupted... though if I try to reconstruct the image with a base64 decoder it works just fine with the file output.

[ARPasescu]

Nevermind, I changed file.store_line() to file.store_string() and it seems to be working without error now.

[groud]

Closing as solved then :)