# Thumbnails

> Create page previews of DOCX and PDF files as PNG, JPG or SVG images with the thumbnails endpoint in curl or .NET: zoom factor, page range and SVG on Linux.

- **Product:** DS Server
- **Section:** Documentation
- **Kind:** Topic
- **Path:** DS Server > Document Processing > Thumbnails
- **1795 words**
- **Web URL:** https://docs.textcontrol.com/ds-server/document-processing/thumbnails/
- **LLMs URL:** https://docs.textcontrol.com/ds-server/document-processing/thumbnails/llms.txt
- **LLMs-Full URL:** https://docs.textcontrol.com/ds-server/document-processing/thumbnails/llms-full.txt

---

A document list with a preview of each file, a template picker that shows the first page of every template, a page overview before a document is signed: all of them need page images. The thumbnails endpoint of the DocumentProcessing Web API renders the pages of a document as images, in the size and format you choose, and returns one image per page.

### How Thumbnails Work

The endpoint is [POST /documentprocessing/document/thumbnails](https://docs.textcontrol.com/ds-server/reference/web-api/documentprocessing/document-thumbnails/post/llms-full.txt):

| Part of the request | Content |
|---|---|
| Body | The document as a Base64 string in a JSON string, with the content type `application/json`. The formats are DOC, DOCX, PDF, TX, XLSX, RTF and HTML |
| `zoomFactor` | The size of the images in percent, from 1 to 400. The default is `100` |
| `fromPage` | The first page to render. The default is `1`, the first page |
| `toPage` | The last page to render. The default, `0`, renders up to the last page |
| `imageFormat` | The image format: `PNG`, `JPG`, `GIF`, `BMP` or `SVG`. The default is `PNG` |
| Response | A JSON array of Base64 strings, one image per page |

`SVG` was added in version 3.2.0. An image format the endpoint doesn't support and invalid page numbers are refused with `400 Bad Request`.

Every request needs an access token, as [Authentication](https://docs.textcontrol.com/ds-server/document-processing/authentication/llms-full.txt) describes.

### Thumbnails on Linux

When DS Server runs on Linux, the Core build doesn't render documents as bitmaps: SVG is its only rendering format, as the changelog of version 4.0 states. Request `imageFormat=SVG` there: `PNG`, `JPG`, `GIF` and `BMP` are bitmap formats. The Core build also supports only DOCX, HTML, PDF and XLSX documents on Linux. [Limits on Linux](https://docs.textcontrol.com/ds-server/overview/core-classic/#limits-on-linux) lists all limits.

### Create Thumbnails With curl

The following commands render the first three pages of *document.docx* at half their size and save each image as a file:

```bash
DS=http://localhost:5000
TOKEN="<access_token>"

# Wrap the Base64 string of the document in a JSON string
base64 -w 0 document.docx | jq -Rs . > document.json

curl --request POST "$DS/documentprocessing/document/thumbnails?imageFormat=PNG&zoomFactor=50&fromPage=1&toPage=3" \
  --header "Authorization: Bearer $TOKEN" \
  --header "Content-Type: application/json" \
  --data-binary @document.json \
  --output thumbnails.json

# Decode each Base64 string of the array into page-1.png, page-2.png ...
count=$(jq length thumbnails.json)
for i in $(seq 0 $((count - 1))); do
  jq -r ".[$i]" thumbnails.json | base64 -d > "page-$((i + 1)).png"
done
```

The commands work as follows:

- `base64 -w 0` encodes the file without line breaks, and `jq -Rs .` makes a JSON string of it, which is the whole body.
- The query parameters select the pages and the size. Leave out `fromPage` and `toPage` to render every page.
- The response is an array with one Base64 string per page. `jq -r ".[$i]"` takes one element without quotes, and `base64 -d` decodes it into an image file.

On Linux, replace `PNG` with `SVG` in the url and save the files as *page-1.svg* and so on.

### Create Thumbnails With .NET

The package `TXTextControl.DocumentServices.DocumentProcessing` returns the images as byte arrays, one per page:

```csharp
using TXTextControl.DocumentServices.DocumentProcessing;
using TXTextControl.DocumentServices.DocumentProcessing.OAuth;

var oauthSettings = new OAuthSettings("<client ID>", "<client secret>");
var documentProcessing = new DocumentProcessing("http://localhost:5000", oauthSettings);

byte[] document = File.ReadAllBytes("document.docx");

// Pages 1 to 3 at a zoom factor of 50 percent
byte[][] pages = await documentProcessing.Thumbnails(document, 50, 1, 3, ImageFormat.PNG);

for (int i = 0; i < pages.Length; i++)
{
    File.WriteAllBytes($"page-{i + 1}.png", pages[i]);
}
```

The code works as follows:

- The `DocumentProcessing` constructor takes the service URL and the credentials of a security profile, and requests an access token.
- `Thumbnails` takes the document, the zoom factor, the first and the last page and an `ImageFormat` value. The package decodes the Base64 strings, so each element of the result is the image file itself.
- `ImageFormat` has the values `PNG`, `JPG`, `BMP` and `GIF` and, in version 5.0.0 of the package, also `SVG`.

Shorter overloads leave out the trailing arguments and create PNG images: `Thumbnails(document)` renders every page at 100 percent, and `Thumbnails(document, zoomFactor)`, `Thumbnails(document, zoomFactor, fromPage)` and `Thumbnails(document, zoomFactor, fromPage, toPage)` set the size and the pages. A longer overload adds a sixth argument, `maxImageResolution`. The package sends it as a query parameter of the same name, with the value `96` when you use an overload without it; DS Server 5.0.2 accepts the parameter, which the endpoint reference doesn't describe. The classes are listed in the [DocumentProcessing namespace](https://docs.textcontrol.com/ds-server/reference/dotnet-api/txtextcontrol-documentservices-documentprocessing/llms-full.txt) of the .NET API.

### Choose the Size and the Pages

- **Size.** `zoomFactor` is a percentage of the page size, from 1 to 400. A value of 100, the default, renders the page at its full size, and smaller values give smaller images for a preview list.
- **First page only.** For a single preview image of a document, set `fromPage=1&toPage=1`, or pass `1, 1` as the page arguments in C#.
- **Every page.** Leave out `fromPage` and `toPage`, or use the overloads without them, and the array has one image for every page of the document.

### Next Steps

- [Converting Documents](https://docs.textcontrol.com/ds-server/document-processing/converting/llms-full.txt): convert the document itself into another format.
- [Document Information](https://docs.textcontrol.com/ds-server/document-processing/document-info/llms-full.txt): read the properties and the merge structure of a document.
- [Supported File Formats](https://docs.textcontrol.com/ds-server/overview/file-formats/llms-full.txt): the formats of each endpoint.
- [Errors and Status Codes](https://docs.textcontrol.com/ds-server/document-processing/errors/llms-full.txt): what a refused request means.

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## Nearby

- **Previous:** [Document Information](https://docs.textcontrol.com/ds-server/document-processing/document-info/llms-full.txt)
- **Next:** [PDF Documents](https://docs.textcontrol.com/ds-server/document-processing/pdf/llms-full.txt)