You will need Photoshop.
- Open texture in Photoshop.
- Convert .jpg (.jpeg) texture to .png to prevent quality loss on subsequential reassemble of texture.
- Next select Slice Tool.
- Draw slice in center of texture
- Next delete this slice, right click on this slice area. You will left with one big slice, sized to whole texture.
- Next click right mouse click on this slice, sized to whole texture, select Divide Slice.
- Next input Horizontal, Vertical row counts, press OK.
- Next click File -> Export -> Save for Web.
- Alt+Mouse Scroll to zoom out from texture preview. Then drag box to select all pieces, select PNG-24 present, disable transparency if needed.
- Click Save, pay attention to Slices option.
- Now you have separate images for pieces. You can reassemble texture using Rw-designer.com, click on Rearrange to change columns count. Or replace card right in the texture, using original card size, image.