How to Make Your Signature a Transparent PNG for Documents
Sign on white paper with a dark pen and photograph it flat in daylight. In Transparent Background, choose Product or object, keep Background on None and download the PNG. Repair gaps with the Restore brush. If a form asks for a JPG signature, it does not need transparency.
When a transparent signature helps, and when it does not
A transparent PNG signature has no paper behind the ink. You can place it on a letter, an invoice or a filled PDF and it sits on the page without a white or grey box around it.
Many online application forms work differently. They ask you to upload a signature image in a set format, often JPG, with a size limit in KB and sometimes exact pixel dimensions. For those, a clean signature on a white background is what is wanted, and transparency adds nothing. Read the form's own instructions first and follow them.
Also check whether a pasted image signature is acceptable at all. Some documents need a handwritten signature on paper or a specific electronic signature process. An image of your signature does not change what a document requires.
Before you take the photo
Most of the quality comes from this step. Sign on clean, plain white paper with a black or dark blue pen. A felt tip or gel pen gives a bolder, more even line than a light ballpoint, which helps the cutout keep every stroke.
Sign a little larger than usual, so the photo holds more detail. Then photograph it in even daylight near a window, with the phone held flat above the paper so the signature is not slanted. Avoid your own shadow or the phone's shadow falling across the page, and turn off the flash, which can leave a bright spot.
Tap the signature on screen to focus before you take the photo. Zoom in on the photo afterwards: if the lines look soft or smeared, take it again. No tool can bring back detail the camera did not capture.
A flatbed scanner works too, and usually gives the most even result.
Make it transparent in SleekCut
Open Transparent Background and drop the photo. In the Subject tab, choose Product or object, which suits logos, drawings and anything that is not a person.
In the Background tab, keep None selected. That is the setting that leaves the area around the ink transparent. White, Colour, Blur and Photo would fill it instead.
Look at the preview. A checkerboard pattern around the ink shows the transparent areas. If thin parts of the strokes look broken or missing, raise Edge detail in the Subject tab. If the edges of the lines look rough or speckled, lower it a little and compare.
When it looks right, download the PNG. Your photo is processed in your browser and is not uploaded.
Fix gaps and leftover paper with the brushes
Signatures are a hard case for any background remover. Strokes are thin, they can be faint where the pen lifted, and dots or short marks can be mistaken for dust. Expect to touch up some results.
Open the Refine tab. Restore paints back parts of the original, so use it on missing strokes, the dot of an i or a faint tail. Erase removes leftover paper texture, shadows or specks.
Under Brush, Smart snaps to the real edges and skips background in between, which suits rough strokes over a line. Exact applies only where you paint, which is better for tiny marks. Set Brush size small for fine work, and pinch or use Ctrl and scroll to zoom in.
Use Compare to see the original and the result side by side. Undo is there if a stroke goes wrong.
Check the downloaded file
Always check the file you will actually use, not the preview. Open the downloaded PNG and place it on both a white page and a dark background. On the dark background, any leftover paper shows up as a pale halo or grey patches around the ink.
Zoom in on the start and end of each stroke. They should be complete and smooth, with no pieces missing.
Then place it in your document at the size it will appear. A signature shown much larger than the photo can support will look soft, so if you need it big, sign larger on paper and photograph it again.
Size, format and cropping
Keep the signature as PNG or WebP if you need transparency. Saving it as JPG fills the transparent areas with white, which is fine for forms that ask for JPG but not for placing on coloured pages.
If there is a lot of empty space around the ink, Crop Image lets you trim it with Free shape so the signature fills the frame. If a form needs exact pixel dimensions, Resize Image lets you type a width and height.
If a form needs a JPG under a certain size, such as 20 KB, use Compress Image or one of its fixed size pages, which saves a JPG and shows the final size and dimensions. Check the result against the form's stated limits before you upload.
Keep your signature safe
A clear image of your signature is personal data. Store it somewhere private, do not post it publicly, and only add it to documents you mean to sign.
Only make a signature image of your own signature, or with clear permission from the person it belongs to for a purpose they agreed to. Delete copies you no longer need, including the original photo in your camera roll and any shared albums.