Ink render plus a one-click spot colour grade: red and orange-red stay, every other hue goes to grey. It draws a Gritty Ink picture on Krea 2 and saves two files per run: the full-colour ink render, and the same picture with only the red accent left in colour. Core ComfyUI nodes only, no custom nodes.
Required models
<ul>
<li>Diffusion model: <a rel="ugc" href="https://civarchive.com/models/958009?modelVersionId=3139241">RedCraft 3.0 Krea 2</a>, the INT8 convrot build, <code>redcraft23_30Krea2_int8_convrot.safetensors</code>, in <code>models/diffusion_models</code>. Plain Krea 2 and Krea 2 Turbo load too; RedCraft is what we tested.</li>
<li>Text encoder: the Qwen3-VL 4B text encoder from the Krea 2 downloads (see <a rel="ugc" href="https://comfyui-wiki.com/en/tutorial/advanced/image/krea/krea-2">the Krea 2 guide on comfyui-wiki.com</a>); we run a community int8 ConvRot build of it (<code>qwen3vl_4b_int8_convrot</code>), and the bf16 or fp8 file works the same. It goes in <code>models/text_encoders</code>, loaded with CLIPLoader type <code>krea2</code>.</li>
<li>VAE: the Qwen-Image VAE, <code>qwen_image_vae.safetensors</code>, in <code>models/vae</code>, from <a rel="ugc" href="https://huggingface.co/Comfy-Org/Qwen-Image_ComfyUI/tree/main/split_files/vae">Comfy-Org on Hugging Face</a>.</li>
<li>LoRA: <a rel="ugc" href="https://civarchive.com/models/3022257">Gritty Ink (Krea 2)</a>, file <code>GrittyInk_Krea2_v1.safetensors</code>, in <code>models/loras</code>. Trigger word <code>grittyink</code>, strength <code>0.8</code>. The workflow does not work without it.</li>
</ul>
Settings
<ul>
<li>Steps <code>8</code>. It is a distilled model, more steps do not help.</li>
<li>CFG <code>1.0</code>, sampler <code>er_sde</code>, scheduler <code>simple</code>, denoise <code>1.0</code>, 1 megapixel sizes (<code>896x1152</code>, <code>1152x896</code>, <code>1024x1024</code>).</li>
<li>Decode: <code>VAEDecodeTiled</code>, tile <code>512</code>, overlap <code>64</code>. Negative: a <code>ConditioningZeroOut</code>, because a negative prompt does nothing at CFG 1.0.</li>
</ul>
How the spot colour works
<ul>
<li>A purple group on the right of the graph (41 core nodes) builds a mask of every pixel whose hue is within <code>hue_width</code> degrees of red (default <code>25</code>), but only where that red is vivid: a chroma floor (default <code>0.2</code>, red minus the weaker of green and blue) greys the dull browns, tans and skin tones that sit in the red hue band, so a fur coat or a wooden post does not keep a muddy colour. Saturated orange up to 45 degrees (fire, lava, lamps, a lit match) is kept as well. Everything outside the mask is replaced by its luminance grey, and the original is pasted back over the grey through the mask.</li>
<li>No HSV node exists in core, so the hue test is done with weighted channel sums (<code>ImageBlend</code>), compared with <code>MaskComposite</code> and <code>ThresholdMask</code>. The READ ME note and the node titles show the values to change: hue width (two nodes, factor = 1 - width/60), chroma floor (two nodes, 0.2; 0 turns it off, 0.3 is stricter), amber hue limit and amber saturation.</li>
<li>Edges are hard, like a colour-range select. The grade is mechanical: a vivid warm tone near the red object survives with it, and a very dull accent can fall under the chroma floor, so lower it if your accent comes out grey.</li>
</ul>
How to use it
<ul>
<li>Keep <code>grittyink</code> at the start of the prompt, write one dense sentence, and name one red, crimson or orange object: an umbrella, a scarf, a pennant, lava, a lit match. That is the colour that survives. With no red or orange in the picture you get plain greyscale ink.</li>
<li>Save node 1 is the ink render, save node 2 is the spot-graded one. You can also feed any picture you already have into the group in place of the decode.</li>
<li>The five hue <code>ThresholdMask</code> nodes hold <code>0.0001</code> on purpose. If your ComfyUI rounds the widget to two decimals, set it back to 0.0001, or other hues leak through.</li>
</ul>
Tips we learned the hard way
<ul>
<li>Density beats brevity. Write a full sentence or two: who or what, where, the light, the camera angle.</li>
<li>Say what you want, never what you do not. No negative prompt, no weight brackets.</li>
<li>One accent. Two red objects dilute the look; a red-and-gold object keeps both.</li>
</ul>
Tested on ROCm (a 7900 XTX), about 13 seconds per run. Core ComfyUI nodes only, so CUDA builds should run it as is.
If this worked for you, a thumbs-up here helps the next person find it.

Krea 2 Ink + Spot Colour (noir comic, one colour left)

Ink render plus a one-click spot colour grade: red and orange-red stay, every other hue goes to grey. It draws a Gritty Ink picture on Krea 2 and saves two files per run: the full-colour ink render, and the same picture with only the red accent left in colour. Core ComfyUI nodes only, no custom nodes.
Required models
<ul>
<li>Diffusion model: <a href="https://civitai.red/models/958009?modelVersionId=3139241" rel="ugc">RedCraft 3.0 Krea 2</a>, the INT8 convrot build, <code>redcraft23_30Krea2_int8_convrot.safetensors</code>, in <code>models/diffusion_models</code>. Plain Krea 2 and Krea 2 Turbo load too; RedCraft is what we tested.</li>
<li>Text encoder: the Qwen3-VL 4B text encoder from the Krea 2 downloads (see <a href="https://comfyui-wiki.com/en/tutorial/advanced/image/krea/krea-2" rel="ugc">the Krea 2 guide on comfyui-wiki.com</a>); we run a community int8 ConvRot build of it (<code>qwen3vl_4b_int8_convrot</code>), and the bf16 or fp8 file works the same. It goes in <code>models/text_encoders</code>, loaded with CLIPLoader type <code>krea2</code>.</li>
<li>VAE: the Qwen-Image VAE, <code>qwen_image_vae.safetensors</code>, in <code>models/vae</code>, from <a href="https://huggingface.co/Comfy-Org/Qwen-Image_ComfyUI/tree/main/split_files/vae" rel="ugc">Comfy-Org on Hugging Face</a>.</li>
<li>LoRA: <a href="https://civitai.red/models/3022257" rel="ugc">Gritty Ink (Krea 2)</a>, file <code>GrittyInk_Krea2_v1.safetensors</code>, in <code>models/loras</code>. Trigger word <code>grittyink</code>, strength <code>0.8</code>. The workflow does not work without it.</li>
</ul>
Settings
<ul>
<li>Steps <code>8</code>. It is a distilled model, more steps do not help.</li>
<li>CFG <code>1.0</code>, sampler <code>er_sde</code>, scheduler <code>simple</code>, denoise <code>1.0</code>, 1 megapixel sizes (<code>896x1152</code>, <code>1152x896</code>, <code>1024x1024</code>).</li>
<li>Decode: <code>VAEDecodeTiled</code>, tile <code>512</code>, overlap <code>64</code>. Negative: a <code>ConditioningZeroOut</code>, because a negative prompt does nothing at CFG 1.0.</li>
</ul>
How the spot colour works
<ul>
<li>A purple group on the right of the graph (41 core nodes) builds a mask of every pixel whose hue is within <code>hue_width</code> degrees of red (default <code>25</code>), but only where that red is vivid: a chroma floor (default <code>0.2</code>, red minus the weaker of green and blue) greys the dull browns, tans and skin tones that sit in the red hue band, so a fur coat or a wooden post does not keep a muddy colour. Saturated orange up to 45 degrees (fire, lava, lamps, a lit match) is kept as well. Everything outside the mask is replaced by its luminance grey, and the original is pasted back over the grey through the mask.</li>
<li>No HSV node exists in core, so the hue test is done with weighted channel sums (<code>ImageBlend</code>), compared with <code>MaskComposite</code> and <code>ThresholdMask</code>. The READ ME note and the node titles show the values to change: hue width (two nodes, factor = 1 - width/60), chroma floor (two nodes, 0.2; 0 turns it off, 0.3 is stricter), amber hue limit and amber saturation.</li>
<li>Edges are hard, like a colour-range select. The grade is mechanical: a vivid warm tone near the red object survives with it, and a very dull accent can fall under the chroma floor, so lower it if your accent comes out grey.</li>
</ul>
How to use it
<ul>
<li>Keep <code>grittyink</code> at the start of the prompt, write one dense sentence, and name one red, crimson or orange object: an umbrella, a scarf, a pennant, lava, a lit match. That is the colour that survives. With no red or orange in the picture you get plain greyscale ink.</li>
<li>Save node 1 is the ink render, save node 2 is the spot-graded one. You can also feed any picture you already have into the group in place of the decode.</li>
<li>The five hue <code>ThresholdMask</code> nodes hold <code>0.0001</code> on purpose. If your ComfyUI rounds the widget to two decimals, set it back to 0.0001, or other hues leak through.</li>
</ul>
Tips we learned the hard way
<ul>
<li>Density beats brevity. Write a full sentence or two: who or what, where, the light, the camera angle.</li>
<li>Say what you want, never what you do not. No negative prompt, no weight brackets.</li>
<li>One accent. Two red objects dilute the look; a red-and-gold object keeps both.</li>
</ul>
Tested on ROCm (a 7900 XTX), about 13 seconds per run. Core ComfyUI nodes only, so CUDA builds should run it as is.

Files with SHA256: 54951d4f57ec9a6fafdc9a3e7c0e35c2cedf2edc56a6c60f257a5162aef37166