Hardware Accurate NES Background Pixel Art

Convert the reference image into authentic 8-bit NES (Famicom) background (BG) dot art pixel graphic adhering strictly to hardware constraints: - Hardware specs: Pure NES BG layer only; sprites strictly prohibited; output canvas resolution of 256x240 pixels; 8x8 pixel tile grid; 16x16 pixel attribute blocks (2x2 tiles). - Cropping and framing: Maintain aspect ratio of the main subject [a medieval castle landscape], centered or cropped to focus on the key subject without stretching or warping. - Palette rules: Strictly limited to the standard 54-color NES NTSC palette. Exactly four 4-color sub-palettes allowed across the entire image. Index 0 is the universal background color shared across all 4 sub-palettes (derived from the most dominant background tone). Each sub-palette contains Index 0 plus 3 unique colors representing shadow, mid-tone, and highlight. - Attribute constraint: Each 16x16 attribute block can strictly use only 1 of the 4 sub-palettes (maximum 4 colors per 16x16 block). - Tile limit: CHR ROM pattern compression applied; maximum 256 unique 8x8 tiles across the entire 256x240 screen, repeating identical tile patterns for sky, terrain, and uniform textures. - Shading: Classic ordered retro video game dithering (checkerboard or line dither) to create smooth gradients using only the 4 available colors per block.