> For the complete documentation index, see [llms.txt](https://mostafaznv.gitbook.io/pdf-optimizer/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mostafaznv.gitbook.io/pdf-optimizer/advanced-usage/configuring-ghostscript/grayimagedepth.md).

# GrayImageDepth

| Method Name    | Argument Name | Argument Type                            |
| -------------- | ------------- | ---------------------------------------- |
| grayImageDepth | depth         | Mostafaznv\PdfOptimizer\Enums\ImageDepth |

Specifies the number of bits per sample in the image. The following values are valid:

* The number of bits per sample: <mark style="color:red;">1 , 2 , 4 , or 8</mark>.
* <mark style="color:red;">-1</mark> , which forces the downsampled image to have the same number of bits per sample as the original image