iApp Image Upscaler

Enlarges an image 2× or 4×, up to 16.8 megapixels, reconstructing edges, texture and lettering rather than blurring them.

POST/v3/store/image-generation/image-upscaler/upscaleTry it

• Price1 ICper request
• Capacity1,500 images/hour
• Served8Kcalls

• v1.0.0-20260907
• Active

Input

file

product.jpg

scale

4

output_format

png

OutputPOST /v3/store/image-generation/image-upscaler/upscale

status

success

model

photo

scale

4

input

width: 800 height: 800

width

3200

height

3200

mime_type

image/png

bytes

9871234

time

model: 0.61 total: 1.42

iapp

images: 1 version: 1.0.0-20260907

Every field, under Response

Request

curl -X POST https://api.iapp.co.th/v3/store/image-generation/image-upscaler/upscale \
  -H "apikey: YOUR_API_KEY" \
  -F "file=@product.jpg" \
  -F "scale=4" \
  -F "output_format=png"

Response

200OK. The fields are explained under Response.

{
  "status": "success",
  "model": "photo",
  "scale": 4,
  "input": { "width": 800, "height": 800 },
  "width": 3200,
  "height": 3200,
  "mime_type": "image/png",
  "bytes": 9871234,
  "image_base64": "iVBORw0KGgoAAAANSUhEUgAADIAAAAyACAIAAAB...",
  "time": { "model": 0.61, "total": 1.42 },
  "iapp": { "images": 1, "version": "1.0.0-20260907" }
}

Request

multipart/form-data, one image per request. 1 IC per image whatever its size or scale; a rejected or failed request is free.

Headers

apikeystringrequired

Your API key, created under API Keys in the control panel.

Body

filefilerequired

The image: JPEG, PNG or WebP, up to 10 MB and 16.8 megapixels. EXIF orientation is applied and transparency preserved. Not needed if image_base64 is sent.

image_base64string

The image as Base64, a data: prefix accepted, in place of file.

scaleinteger

4, the default, or 2. At 4× the input may be up to 1024 × 1024; at 2×, up to 2048 × 2048.

modelstring

photo, the default, for photographs; anime for illustrations and flat artwork; fast when throughput matters more than detail.

output_formatstring

png, the default and lossless, jpeg or webp. A 4096 × 4096 photograph is 10 to 20 MB as PNG and 1 to 3 MB as JPEG at quality 92.

qualityinteger

1 to 100 for jpeg and webp. Default 92.

responsestring

json, the default, returns the object in the panel with the image as Base64; image returns the bytes with the matching Content-Type.

GET /v3/store/image-generation/image-upscaler/models lists the models and limits, free.

Response

The model and scale used, the input size, the output width and height, mime_type, bytes, image_base64, and time: model for the enlargement, total including decoding the upload and encoding the result. Every success carries the headers iapp-input-images: 1 and x-iapp-output-size.

The model and scale used, the input size, the output width and height, mime_type, bytes, image_base64, and time: model for the enlargement, total including decoding the upload and encoding the result. Every success carries the headers iapp-input-images: 1 and x-iapp-output-size.

Status codes

Code	error_code	Meaning
400	invalid_image	Not a readable JPEG, PNG or WebP
400	input_too_large	The input is over 16.8 megapixels
400	output_too_large	Input × scale would pass 16.8 megapixels; the message gives the largest input for that scale
400	invalid_scale, invalid_model, invalid_output_format	A field outside the values above
413	file_too_large	The upload is over 10 MB
503	starting	The service is starting; retry after 30 seconds

Details

Measured

The photo model against plain bicubic resizing on the 29 images of the iApp Image Generation gallery, 900 × 540, each reduced 4× and enlarged back, 7 September 2026.

Measure	Bicubic	Upscaler
LPIPS perceptual distance, lower is better	0.284	0.159
Images where the upscaler is closer to the original		29 of 29
PSNR, higher is better	27.2 dB	25.7 dB

LPIPS measures how close the result looks to a person; PSNR rewards the safe blur of a resize, so reconstructing texture always costs a little of it.

Time, production GPU, median of 5	Model	PNG encode	JPEG encode
512 × 512 to 2048 × 2048	0.23 s	0.34 s	0.05 s
1024 × 1024 to 4096 × 4096	0.98 s	1.37 s	0.18 s
1920 × 1080 to 3840 × 2160	0.41 s	0.61 s	0.08 s
2048 × 2048 to 4096 × 4096	0.78 s	1.27 s	0.18 s

For 1024 × 1024 to 4096 × 4096 the illustration model takes 0.32 s and the fast model 0.06 s. One GPU serves about 1,500 images per hour at the largest output as PNG and about 3,000 as JPEG; beyond that, requests queue.

Limits

• Rate limits per key: 5 per second, 60 per minute, 1,200 per hour.
• Fine detail absent from the source is invented, not recovered: a face or small text at 40 pixels comes out sharp but not necessarily true, so the output is not evidence of what a low-resolution source showed.
• Compression and blur in the source are cleaned up; motion blur and out-of-focus areas stay soft.

Data handling

Images are processed in memory and returned in the response; nothing is written to disk or kept. The model runs on iApp's own GPUs in Thailand, and no image goes to a third party. The service is GDPR and PDPA compliant.

Changelog

Version	Date	Changes
v1.0.0-20260907	7 Sep 2026	First release: 2× and 4× with the photo, illustration and fast models, PNG, JPEG and WebP output up to 16.8 megapixels with transparency preserved, at 1 IC per image.