You can provide image data for prediction to the Vertex AI API by sending the image data as Base64-encoded text.
Using the command line
Within a gRPC request, you can simply write binary data out directly; however, JSON is used when making a REST request. JSON is a text format that does not directly support binary data, so you will need to convert such binary data into text using Base64 encoding.
Most development environments contain a native base64
utility to
encode a binary into ASCII text data. To encode a file:
Linux
Encode the file using the base64
command line tool, making sure to
prevent line-wrapping by using the -w 0
flag:
base64 INPUT_FILE -w 0 > OUTPUT_FILE
macOS
Encode the file using the base64
command line tool:
base64 -i INPUT_FILE -o OUTPUT_FILE
Windows
Encode the file using the Base64.exe
tool:
Base64.exe -e INPUT_FILE > OUTPUT_FILE
PowerShell
Encode the file using the Convert.ToBase64String
method:
[Convert]::ToBase64String([IO.File]::ReadAllBytes("./ INPUT_FILE ")) > OUTPUT_FILE
Create a JSON request file, inlining the base64-encoded data:
JSON
{ "instances" : [ { "content" : " BASE64_ENCODED_DATA " } ], "parameters" : { "confidenceThreshold" : DECIMAL , "maxPredictions" : INTEGER } }
Using client libraries
Embedding binary data into requests through text editors is neither desirable or practical. In practice, you will be embedding base64 encoded files within client code. All supported programming languages have built-in mechanisms for base64 encoding content.
Python
# Import the base64 encoding library.
import
base64
# Pass the image data to an encoding function.
def
encode_image
(
image
):
with
open
(
image
,
"rb"
)
as
image_file
:
encoded_string
=
base64
.
b64encode
(
image_file
.
read
())
return
encoded_string
Node.js
// Read the file into memory.
var
fs
=
require
(
'fs'
);
var
imageFile
=
fs
.
readFileSync
(
'/path/to/file'
);
// Convert the image data to a Buffer and base64 encode it.
var
encoded
=
Buffer
.
from
(
imageFile
).
toString
(
'base64'
);
Java
// Import the Base64 encoding library.
import
org.apache.commons.codec.binary.Base64
;
// Encode the image.
String
encodedString
=
Base64
.
getEncoder
().
encodeToString
(
imageFile
.
getBytes
());
Go
import
(
"bufio"
"encoding/base64"
"io"
"os"
)
// Open image file.
f
,
_
:=
os
.
Open
(
"image.jpg"
)
// Read entire image into byte slice.
reader
:=
bufio
.
NewReader
(
f
)
content
,
_
:=
io
.
ReadAll
(
reader
)
// Encode image as base64.
base64
.
StdEncoding
.
EncodeToString
(
content
)
