Image preprocessing

Preprocessing runs once on the source image, before any format is rendered. That is what keeps a watermark or a hue shift consistent across the whole kit — and it is also why a setting that looks fine on a 1080×1080 square can look wrong on a 2480×3508 print sheet.

The order of operations is fixed:

1. Background removal
2. Background colour / gradient fill
3. Edge smoothing
4. Noise reduction
5. Auto-crop
6. Colour operations — grayscale, B&W, invert, hue, temperature, saturation, brightness, contrast
7. Sharpen or blur
8. Vignette
9. Drop shadow
10. Watermark

Colour

Control	Form field	Default	What it does
Grayscale	grayscale	false	Converts to luminance, keeping the alpha channel
Black & white	bw	false	Hard threshold to pure black and white — no midtones
Invert	invert	false	Inverts RGB, leaves alpha alone
Hue shift	hue_shift	0	Rotates hue in degrees, −180 to +180
Temperature	temperature	0	Warm (positive, boosts red) to cool (negative, boosts blue), −100 to +100
Saturation	saturation	1.0	0.0 is fully desaturated, 1.0 is unchanged, >1.0 boosts
Brightness	brightness	1.0	Same scale as saturation
Enhance contrast	enhance_contrast	false	Applies an autocontrast pass

Grayscale vs B&W

grayscale is what you want for a monochrome logo variant. bw is a hard threshold — useful for testing whether a mark survives being reduced to a stencil, rarely useful as a deliverable.

Sharpness and blur

Control	Form field	Default	Notes
Sharpen	sharpen	false	Unsharp mask
Sharpen radius	sharpen_radius	1.0	Larger radius, coarser halo
Blur	apply_blur	false	Gaussian blur
Blur radius	blur_radius	2	In pixels, at source resolution
Noise reduction	noise_reduction	false	Median filter; needs OpenCV for the stronger path
Noise strength	noise_strength	1	Integer; higher is more aggressive and softer
Enhance quality	enhance_quality	false	Combined contrast + sharpness + colour pass

Sharpen and blur are mutually antagonistic — turning both on will apply both, in that order, and you will get a soft image with ringing. Pick one.

Composition

Control	Form field	Default	Notes
Auto-crop	auto_crop	false	Trims uniform borders down to the content bounding box
Crop padding	crop_padding	10	Pixels of margin left around the content after trimming
Vignette	vignette	false	Darkens the edges radially
Vignette strength	vignette_strength	0.5	0.0–1.0

Auto-crop is the single most useful control here. If your logo has a lot of empty canvas around it, every format will render it small and lost. Auto-crop with 10–20 px of padding fixes that once, for all formats.

Drop shadow

Control	Form field	Default
Enable	shadow_effect	false
Opacity	shadow_opacity	0.3
Blur radius	shadow_blur	4
Offset X	shadow_offset_x	5
Offset Y	shadow_offset_y	5

The shadow is drawn from the alpha channel, so it only produces something meaningful on an image that actually has transparency — either a source PNG with an alpha channel or the output of background removal.

Watermark

Control	Form field	Default
Enable	add_watermark	false
Text	watermark_text	© BrandKit
Opacity	watermark_opacity	0.3

The watermark is rendered with Pillow's default bitmap font unless a TrueType face is available on the host, so it will look coarse on very large canvases. Set your own default text in config.json.

Output encoding

These two are not preprocessing — they apply at encode time, per generated file.

Control	Form field	Default	Notes
Quality	quality	95	JPEG and WebP only; PNG and ICO ignore it
Strip metadata	strip_metadata	false	Drops the ICC profile and remaining metadata from generated files

EXIF is always stripped from the upload

Regardless of the strip_metadata switch, the uploaded original is re-encoded through Pillow immediately on receipt, which discards EXIF — including GPS coordinates and camera serial numbers. strip_metadata controls the generated files only. See Privacy.

Changing the defaults

Every default above lives in preprocessing_options in config.json. Edit it there and the UI starts with your values.