【画像生成AIの進化】「にじジャーニー」がたどったアニメ表現の軌跡
AI での画像生成では、アニメ風 か、実写風 なのか、という２つのスタイルに分かれます。そのアニメ風の中でも得意な分野を築いたスタイルがあります。
アニメやイラストの表現に特化し、世界中のクリエイターを魅了し続けている画像生成AI「にじジャーニー（nijijourney）」。その進化は、私たちが頭の中で描く「2次元の世界」をどれだけ忠実に、そして美しく画面に映し出せるかの歴史でもあります。
今回は、そのスタイルがどのように移り変わってきたのかを3つのステップで振り返ります。
1. 黎明期：アニメ表現への挑戦
最初は「AIに日本のアニメ風の絵を描かせる」こと自体が大きな挑戦でした。当時は手足のバランスが崩れたり、どこか西洋画のようなタッチが混ざったりと、思い通りの線を出すには試行錯誤が必要な時代でした。
2. 多様性の獲得：「4つのスタイル」の誕生
大きな転換点となったのが、好みの絵柄を選べるようになった時期です。 プロンプトの指定ひとつで、以下のような異なる世界観を自在に呼び出せるようになりました。
Default: 彩度が高く、王道で華やかなアニメ調
Expressive: 海外のコンセプトアートを思わせる大人びたタッチ
Cute: デフォルメされた可愛らしいデフォルメ風
Scenic: キャラクターよりも背景の美しさや空気感を重視したスタイル
3. 最新：無限に広がる表現の引き出し
そして現在では、描写の精度が飛躍的に向上。単なる「綺麗なアニメ絵」にとどまらず、鉛筆のラフスケッチ風、水墨画、Gペンで描いたような繊細な線画、さらには個人の作風を取り入れる機能まで備わるようになりました。
AIが単なる「ツール」から、クリエイターの表現の幅をどこまでも広げる「良き相棒」へと進化を遂げた現在。にじジャーニーは、個性を描き分ける成熟したステージへと突入しています。
画像生成AI である stable diffusion においてもこのスタイルを取り入れたモデル(チェックポイント) がいくつもあります。
その中でも私が使っているのは SDVN7-NijiStyleXL というモデルです。
このモデルを使う場合、プロンプトの中に必ず、(niji style) と入れることでこのモデルの特徴が発揮されます。
以下、作例とそのプロンプトを紹介します。
masterpiece, best quality, ultra-detailed, 1girl, solo, beautiful detailed eyes, intricate hair, standing in a magical glowing forest, soft lighting, rim lighting, vibrant colors, anime art style, niji style, by key visual, delicate line art Negative prompt: lowres, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry Steps: 24, Sampler: Euler a, Schedule type: Karras, CFG scale: 4.5, Seed: 2240654302, Size: 988x1408, Model: sdvn7Nijistylexl_v1, Model hash: 6e0ba74ac1, RNG: CPU, Version: neo-2.27
niji style, masterpiece, best quality, ultra-detailed, anime art style, niji style, an extremely detailed close-up illustration of a Japanese short-hair calico cat deeply asleep on a weathered wooden Engawa (Japanese traditional porch). The cat with orange, black, and white fur is curled comfortably, bathed in soft, warm natural daylight filtering through a nearby shoji screen. Peaceful face, gently closed eyes, tiny pink nose, relaxed whiskers. Soft fluffy fur texture, aged wood grain. The background features a blurred shoji screen and a mossy Japanese garden with hydrangeas, strong bokeh. Quiet, peaceful, tranquil atmosphere, Studio Ghibli style, beautiful digital painting. Steps: 24, Sampler: Euler a, Schedule type: Karras, CFG scale: 4.5, Seed: 2058493005, Size: 988x1408, Model: sdvn7Nijistylexl_v1, Model hash: 6e0ba74ac1, RNG: CPU, Emphasis: Original, Version: neo-2.27
masterpiece, best quality, ultra-detailed, anime art style, niji style, 1boy, 1girl, couple, holding hands and dancing together in a bright park, dynamic pose, spinning, smiling, happy cheerful expressions, sunlight filtering through trees, dappled sunlight, lush green foliage, blooming flowers, park pathway, casual summer outfits, wind blowing hair, soft focus background, magical atmosphere, vibrant colors, illustration, by key visual
Negative prompt: lowres, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry, realistic photo, 3d render, ugly
Steps: 24, Sampler: Euler a, Schedule type: Karras, CFG scale: 4.5, Seed: 3425834760, Size: 1536x960, Model: sdvn7Nijistylexl_v1, Model hash: 6e0ba74ac1, RNG: CPU, Version: neo-2.27
masterpiece, best quality, ultra-detailed, anime art style, niji style, 1girl, solo, standing on an old wooden pier over the ocean, looking out at the sea, windy atmosphere, dynamic motion, holding onto her wide-brimmed white sun hat to keep it from blowing away, long white flowing dress fluttering violently in the wind, hair blowing wildly, dramatic sky with heavy clouds, flock of seagulls flying in the distance, salty air, cinematic lighting, emotional expression, detailed background, breeze
Negative prompt: lowres, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry, realistic photo, 3d render, stiff pose
Steps: 24, Sampler: Euler a, Schedule type: Karras, CFG scale: 4.5, Seed: 2176123952, Size: 1536x960, Model: sdvn7Nijistylexl_v1, Model hash: 6e0ba74ac1, RNG: CPU, Version: neo-2.27
masterpiece, best quality, ultra-detailed, anime art style, niji style, 1girl, solo, standing on an old wooden pier over the ocean, looking out at the sea, windy atmosphere, dynamic motion, holding onto her wide-brimmed white sun hat to keep it from blowing away, long white flowing dress fluttering violently in the wind, hair blowing wildly, dramatic sky with heavy clouds, flock of seagulls flying in the distance, salty air, cinematic lighting, emotional expression, detailed background, breeze
Negative prompt: lowres, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry, realistic photo, 3d render, stiff pose
Steps: 24, Sampler: Euler a, Schedule type: Karras, CFG scale: 4.5, Seed: 3965993810, Size: 960x1536, Model: sdvn7Nijistylexl_v1, Model hash: 6e0ba74ac1, RNG: CPU, Version: neo-2.27
masterpiece, best quality, ultra-detailed, anime art style, niji style, 1girl, solo, close-up, upper body shot, low angle shot, looking down at camera, dramatic angle, intense gaze at the viewer, wind blowing hair wildly across face, holding onto a wide-brimmed white sun hat with one hand to secure it, wearing a white summer dress, background is blurred deep blue ocean and dramatic cloudy sky, flying seagulls, dynamic lighting, emotional, serious yet beautiful expression
Negative prompt: lowres, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry, realistic photo, 3d render, distorted face, bad proportions
Steps: 24, Sampler: Euler a, Schedule type: Karras, CFG scale: 4.5, Seed: 2057335198, Size: 960x1536, Model: sdvn7Nijistylexl_v1, Model hash: 6e0ba74ac1, RNG: CPU, Version: neo-2.27
niji style, best quality, masterpiece, delicate, intricate details, a close-up portrait of a cute young girl sitting in a vast, vibrant wildflower meadow. She is focused intently on weaving a flower crown with her small, gentle hands. Her face is in soft focus, illuminated by warm, golden hour sunlight filtering through her slightly messy, light brown hair (decorated with a few small braided flowers). She has a peaceful, concentrated expression with a small, gentle smile. The foreground is filled with a rich variety of detailed wildflowers (lavender, chamomile, daisies, clover) and greenery, creating a shallow depth of field (bokeh). The flowers are held close to her chest as she weaves. Her clothing is simple, cozy, and natural (e.g., a linen dress in a soft pastel color). The background is a beautiful, completely blurred (strong bokeh) sea of colorful flowers and distant trees under a soft, diffused sky. High-resolution, cinematic lighting, soft color palette, emotional and dreamy atmosphere.
Steps: 24, Sampler: Euler a, Schedule type: Karras, CFG scale: 4.5, Seed: 2939654443, Size: 1408x1088, Model: sdvn7Nijistylexl_v1, Model hash: 6e0ba74ac1, RNG: CPU, Emphasis: Original, Version: neo-2.27
いいなと思ったら応援しよう！
応援よろしくお願いします！ 皆さまのチップが写真撮影やAI作画の活動を支えています。チップをいただくことで、さらに魅力的な作品を制作し、お届けすることができます！ぜひ、ご支援をお願いいたします！